On the track of deep-sea sponges…

Hello dear SONNE friends!

Today’s blog entry is about the work of Prof. Dr. Gert Wörheide.
The following report was written by Gert Wörheide. He is a professor at the Ludwig-Maximilians-University (LMU) Munich and one of the sponge experts here on board of the R/V SONNE.

Prof. Dr. Gert Wörheide is taking samples in the wet lab of the R/V SONNE


Today it is time to report something about the work of the sponge team, which busily investigates the diversity of deep-sea sponges using the ROV KIEL6000. But what is the first question once a new sponge comes into focus and later lands on deck? What species is this? And here I come into the game!

I am a Professor at the Department of Earth and Environmental Sciences at the Ludwig-Maximilians-Universität (LMU) München and a specialist for the so-called “DNA Barcoding” and molecular taxonomy and systematics of sponges. I am here on board as a member of the “sponge team” led by Prof. Peter Schupp of the ICMB, and my task is to identify the collected sponges using molecular methods.

But stop, can sponges not be identified readily from pictures? No, not really. A few species can be, but the vast majority of sponges can only be identified by experts, based on skeletal features – a long and tedious process…

To find a way to shorten the process of sponge species identification, some colleagues and myself initiated in 2006 the “Sponge Barcoding Project“, which aims at identifying sponges based on so-called “Barcoding” sequences. These “Barcoding” sequences are sequences of species-specific gene fragments from the mitochondrial, and for sponges often also the nuclear, genomes that are species specific and can be used to identify species. Using these DNA Barcodes, larger collections from biodiversity surveys such as this one, with more than 400 collected samples, can relatively quickly be identified to ansqwer questions about the biodiversity of the sampled habitats. DNA sequences also have the advantage that phylogenetic relationships can be estimated by comparative sequence analyses, so we can learn a lot more about the evolution of the deep-sea sponge communities, for a better understanding of the deep-sea ecosystem as a whole.

My task here on board is to subsample each sponge (but also octocorals and echinoderms) and preserve three of these subsamples using different chemicals, such as RNAlater and nearly pure Ethanol. Doing so enables subsequent molecular studies, besides DNA barcoding also further in-depth transcriptomic and genomic studies. All these analyses will be carried out by my team and myself back home in the lab in Munich, to unlock the secrets of the deep-sea sponges…

The sponge team led by Prof. Dr. Peter Schupp (LTR: Dr. Jackson Cahn, Klaus Peter Conrad, Lars-Erik Petersen, Dr. Sven Rohde, Prof. Dr. Gert Wörheide, Prof. Dr. Peter Schupp, Dr. Dennis Versluis, Tessa Clemens, Tanja Stratmann, Kathrin Busch, Sadie Mills). Besides identification, research focusses mainly on physiology and chemistry of sponges and their associated microbes.