How can tropical coral reefs be so diverse and productive? And how do sponges make sure the coral reef can persist as biological hotspot? Sponges are indeed important animals in a variety of marine and freshwater ecosystems (they even occur in the canals of Amsterdam). Apart from their ecological significance, sponges are found to be interesting organisms in a wide variety of scientific fields. From an evolutionary point of view, they are the oldest known multicellular organism on Earth, more than 700 Million years old. Moreover, they show a striking resemblance to the human gastro-intestinal tract. From a biotechnological point of view, they are considered to be chemical factories; Most of the 15.000 known sponge species (there are only about 5.000 mammals on this planet) produce substances that can lead to the development of new medicines against cancer and HIV, new anti-biotics, food supplements and biomaterials.
In our group, we are interested in two main subjects: the functioning of highly productive ecosystems thriving in oligotrophic (nutrient-poor) waters and the physiology of sponges and their associated microbes. We try to be question-driven and use a wide variety of experimental approaches and techniques to answer our questions, from molecular- to cell- to ecosystem level. More important: We strongly emphasize the power of fundamental research as an innovative basis leading to application. This approach requires a close collaboration with (inter)national specialists in both science and commerce. Together with Dr Ronald Osinga from the Wageningen University, I'm co-owner of the research-driven Blue-Biotech company Porifarma BV (www.porifarma.com).
Sponges are a close collaboration with numerous microbes and are known as biotechnological 'milk-cows'. There is one problem, though: We are (yet) not able to grow them under controlled conditions, for example in artificial seawater aquaria. Our group was to first to collaborate with pathologists and cell biologists from the Maastricht University to discover how sponge cells are growing and being lost. In fact, sponges showed the fastest cell cycle of any multicellular organism found to date. The cell biology of sponges now gives the oppertuntity to determine the 'state' of a sponge: Is it growing, or in steady state, maybe regenerating? This helps us to understand and, ultimately, control the growth of sponges in aquaria. Sponges also show a striking resemblance to a human colon, which makes it an interesting animal model for cancer research and as an uptake system.
Per square meter, a coral reef produces more energy than most human factories are able to. The coral, however, occurs in tropical, oligotrophic waters, also known as the marine equivalent of a desert. Therefore, it has tight and very efficient recycling mechanisms that prevent energy nutrients to leak from the ecosystem. In other words: the system is highly productive, without leaking waste. This knowledge leads to create sustainable ways of aquaculture, the so-called Sustainable Integrated Ocean Farming (SIOF). We aim to understand the functioning of the natural coral reef ecosystem. Recently, we discovered how sponges are at the base of a recycling mechanism we refer to as the "Sponge Loop". The important role of sponges helps to better understand and protect coral reefs, which are in worldwide peril.