Royal Netherlands Institute for Sea Research

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Dissolved Organic Matter on Coral Reefs

Corals and Algae photosynthesize and thereby capture the sun's energy into carbon based molecules like sugars, lipids, proteines but also hormones and and other secondary metabolites. Corals and Algae release part of these molecules into the watercolumn as dissolved organic matter (DOM). All this captured energy is not lost at sea: while bigger organisms cannot use this dissolved organic matter, bacteria can! Because bacteria can use this dissolved organic matter for growth, the energy can be passed along the foodchain when these bacteria are eaten by the herbivores, who are next in line.

In our oceans, it is estimated that 'only' 3 gigatones of Carbon make up marine biota (mainly in microbial form), this in comparison to 700 gigatons of marine Dissolved Organic Carbon. This means that microbes are floting around in a sea of food. But for long we only could measure the total amount of food, and measure how much was left after microbes had been eating it. With the current techniques we get an insignt in the molecular makeup of DOM.

DOM is like tea, dissolved and in many different flavors
Corals and Alage release their own set of molecules and thereby making their own blend of tea, depending on molecular makeup and their concentrations. We know that when we grow microbes on either coral or algal DOM, the microbial community changes. With coral reefs changing from high coral cover to high algae cover, we can expect that the 'blend' of a reef changes and thereby the microbial communty in the water.
During my PhD I aim to understand what the similarities and differences are in the released DOM by corals and Algae. What part of the DOM pool is 'consumed' by the microbial community? and how does that effect the microbial communty? In addition, stress like coral bleaching changes corals drasticly and it is expected that it will change the released DOM of the coral. But what changes? do microbes find that more or less yummy? what are the effects of changes on the molecular scale and what are the possible effects on ecosystem levels?


I have had the privilige to conduct fieldwork for my Ph.D. on both the island of Curacao and Mo'orea (French Polynesia). During my Masters at the University of Amsteram I had two research internships: the first one under supervision of Dr. Fleur van Duyl here at NIOZ, with fieldwork in Curacao.  The second research internship was at San Diego State University, USA, under the supervision of Dr. Forest Rohwer.
I have obtained my Bachelors' degree from Utrecht University in Biology and there for my research internship I joined the lab of Dr. Anastazia Banaszak, from UNAM, in Puerto Morelos, Mexico.