Growth rate and green fluorescence analysis by 3D photogrammetry and imaging of natural & Biorock Corals on the Caribbean Sea.

Supervisor: Tom Goreau (Global Coral Alliance, Panama).
At the present situation, coral reefs, highly vulnerable ecosystems are among the most diverse and richest ecosystems on earth, they have been suffering massive decline through in the past decades due to both anthropogenic and natural factors. As a consequence, different conservation and restoration methodologies have been developed, among which the mineral accretion technique, Biorock, stand out. This technique is based on the immersion of any conductive material in sea water and the posterior deposit of calcium carbonate on this conductive structure boosted by the application of a reduced current which generates the mineral deposit on this support. Mineral deposit formed on the structure surface acting as a cathode along with the reduced current flowing on the steel structure has been shown on previous studies (Goreau & Hilbertz, 2005) to increase growth rates in a wide range of marine organism, among them, corals. In the case of these important organisms it also have shown to increase % survival after bleaching events or disease appearance in corals affected by Biorock. In this study different methodologies to assess coral health are proposed in order to look for any difference between corals on Biorock structures and corals not affected by this electro-stimulated method in natural and artificial control structures. Two kind of methodologies will be used to assess coral status. On the one hand, the coral growth will be studied in 2 and 3 dimensions since the 3D complexity is also a very important factor that is not always studied on coral reef monitoring (Ferrari et al., 2017). 2D analysis will be realised by imaging coral species and processing of the images with ImageJ software. 3D analysis will be taken place by Photogrammetry, a rising methodology to study coral growth and 3D complexity evolution, in this case, Autodesk RECAP software will be used for the 3D modelling & comparison between models along the study. On the other hand, another monitoring method will be taking place, Green-fluorescence Imaging, also a rising methodology in the research community as an economic alternative to study green fluorescence proteins (GFP) on coral tissues, avoiding the use of expensive devices as spectrometers and obtaining information about the heterogeneity on the distribution of these proteins along the coral colony. Even if the exact function of these GFP is not still clear, this experiment will pay attention to the change on relative concentration and distribution of the proteins. Being the objective of this study to highlight differences on growth and green florescence between the different coral spp. present on Biorock and control structures, no signicative differences were found between these 2 groups. The results suggest longer time-scales to be used on future experiments and more diverse coral populations on each experimental group. Also more controlled experiences on laboratory are recommended to avoid biases by different parameters out of our control on the field as pH, salinity, temperature, excess of nutrients and pollution; especially on the GFP case due to due to the unknown that continues to perform its functions or regulation.