The role of sponge competition in cold-water coral reefs - ROV video analyses and secondary metabolite profiling

Coral Reefs are important for climate regulation, food and energy supply their potential for bioprospecting and cultural services. Unlike tropical coral reefs, cold-water corals (CWC) can grow in the dark, are slow growing and rely on catching food themselves. Due to their remote and inaccessible nature, studies on the ecological interactions (competition, symbiosis) and bioprospecting of CWC reef organisms remain scarce.

This interdisciplinary 4 year-long PhD project will investigate the ecological role of the sponge Mycale lingua by integrating data from (a) long term Remotely Operated Vehicle (ROV) video data spanning over ten years, (b) secondary metabolite profiling, (c) microbiome DNA profiling, in the search for compounds of medical and ecological relevance.

The Norwegian CWC Tisler Reef has high densities present of the sponge M. lingua and it is speculated that previous trawl damage has weakened the reef and gave a competitive advantage to the sponges, now seemingly overgrowing the reef. However, there is no evidence on this and instead sponges are known to provide and recycle nutrients that benefit CWC reefs.

ROV videos will be used to look at long term spatial and temporal changes in the growth pattern of the sponges. This will be integrated with data on the secondary metabolite profile (metabolome) from sponges collected as part of the ASSEMBLE Plus AmpLOPHELIA project and whether the secondary metabolites provide the sponge with a competitive advantage.

The metabolome of sponges will be analysed using liquid chromatography-mass spectrometry and MS-MS networking. Additional samples will be collected to show the variation of the metabolome in space and time. Unique clusters of metabolites will be identified, and the compounds isolated, and structures determined using spectroscopic methods. This will then allow the evaluation of the bioactivity of the compounds in a variety of ecologically and medically relevant biological assays and pave the way for future chemical ecology studies on M. lingua. The sponge microbiome will be analysed by isolating the metagenome of the sponge microbiome and analysing the DNA using the relevant primers followed by sequencing and bioinformatic analysis. Variations in the metagenome and metabolome will enable conclusions to be drawn about the which factors have made this sponge successful and allow future hypothesis driven field research on this question.

This PhD project will be supervised by Prof Marcel Jaspars and Dr Laurence De Clippele. Marcel Jaspars is an expert in marine bioprospecting and has discovered several marine derived compounds with activity in animal models (Cancer, Alzheimer's, Epilepsy) or patented and licenced to industry (bacterial infection). He will provide supervision in the metabolomics, metagenomics, compound isolation and identification aspects of the project. Laurence is an expert in cold-water coral reef ecology and video analyses and has extensive experience working at the Tisler reef. She will provide supervision on the ecological interpretation of the data and the video analyses.

This project offers multidisciplinary training in: 1.) Sponge ecology and image analysis; 2.) Metagenomics and bioinformatics; 3.) Metabolomics using LC-MS/MS and statistical methods; 4.) Secondary metabolite chemistry and spectroscopy.