Microbiome Productivity: investigating the photophysiology and productivity of microalgal biomes in coralline algal habitats

This project utilises the expertise of the UK partners regarding macro and microalgal taxonomy, ecology and physiology, in a novel collaboration with the French partners regarding single cell analysis of samples using the combination of Hyperspectral Imaging and high resolution fluorescence. The subject matter will be the combination of the bioengineer Coralline macroalgae and the epi and endo biotic microalgal biome associated within the fronds of these macroalgae. This is a value added investigation expanding upon a NERC UK Ocean Acidification research Programme studentship project supervised by the UK partners. Coralline macroalgae are calcifying organisms that engineer a 3-dimensional habitat colonised by many endobiotic and epibiotic organisms. A large part of this community is comprised of photosynthetic microalgae. These are important biomes, yet are extremely poorly understood with regard to basic knowledge of community structure, or the functional relevance or interaction of the microalgae and the macroalgae. This project therefore aims to establish a long term collaboration between the UK and French partners, investigating the two photosynthetic components of the biome with regard to community structure, primary productivity and functional photophysiology. Initial pilot data obtained by the PI and the French partners using seagrass (Zostera species) has indicated that paired hyperspectral imaging and high resolution fluorescence imaging produces spectral signatures that can identify the major taxa dominating the epiphytic community growing on the Zostera. Further analysis suggests that this data, paired with high resolution fluorescence may enable analysis of primary productivity, photosynthetic pigments and functional photophysiology (e.g. down regulation, photoacclimation etc.) of individual single cell epiphytes as well as individual segments (intergenicula) of the macroalgal frond. If this proves correct, then the novel pairing of these methods will provide ultra-fine scale data on the photophysiology and productivity of the macroalgae, the microalgae and the interaction between the two. This will greatly expand our understanding of the function of the macro and micro components of these important communities and hence enable a far more informed interpretation of photophysiological data when investigating impacts, such as acidification and light induced stressors, or enhanced carbon dioxide treatments, applied in studies of these important coastal organisms.

The project will have the following impacts:-
Level 1: Immediate impact - researchers on algal photobiology and coastal ecosystems.
The data obtained from this project will be the first of its kind at the fine scale resolution of individual epiphyte cells and macroalgal intergenicula. This is of key importance in understanding the productivity and photobiology of the microalgae and how this interacts within the epiphytic microalgal biome. Currently work in this field integrates the data obtained without the ability to split the data between the epiphytes, the epiphyte taxa and the host macroalgal frond. In addition the effects of shading and age of the frond are largely ignored with no differentiation of data between the subsections of the macroalgal frond, e.g. across the apical tip to the basal plate and on the upper and underside of each section. Furthermore, this project will achieve high accuracy GIS images pairing the hyperspectral data on pigments and photophysiological parameters, with those of the high resolution fluorescence data on productivity and photoacclimation parameters. Again this is completely novel at the fine scale of the Corallina intergenicula and the epiphyte cell levels. This will provide major advances in the field of knowledge of macro and microalgal photobiology.
Level 2: Researchers investigating environmental impacts of ocean acidification and climate change in general
Data on impacts of stressors such as reduced pH as part of ocean acidification studies etc., have used the integrated data on productivity and other photophysiological parameters. This has been in the absence of data on the inherent variability of these parameters within the macroalgal frond and also within the microalgal epiphyte community as described above. Thus data have been inaccurate as differences between experimental treatments have had differences due to other environmental and biological factors being included within the error of the data measurements, with no knowledge of the level of error of the actual treatment as opposed to that of factors described above. The large scale dataset obtained from this project will address this and enable far more precise determination of true differences within samples to be attributed to experimental factors, once the roles of the epiphytes can be determined and the variability within the macroalgal frond also determined as a factor of position within the frond and sample age.
Level 3: End users interpreting environmental stress impacts on coastal ecosystems
Inherent within the Level 2 impacts will be the ability of non-expert end users to be provided with data on the accuracy of experimental findings from investigations into environmental stressors such as those of climate change and ocean acidification. Thus end users will be better informed on the real effects of such impacts.
Level 4: Education impacts via research led teaching
The findings of the project and the data obtained will be of high use to those teaching on photobiology, macroalgal ecology and other biological aspects.
Level 5: Collaboration between the research partners
The project findings will facilitate further grant applications between the Nantes and UK partners to facilitate further work in this field. This is in addition to the value added nature of the project with respect to the NERC UKOARP project of the UK partners investigating the effects of ocean acidification on calcifying Corallina macroalgae.