“The challenges facing the ocean require collaboration across borders and generations”

The OceanConnectXL alumni event will take place in Ostend on 16 November. Neither the location nor the date was chosen by chance.
“We are using the facilities of VUB aan Zee, VUB’s research and innovation hub in Ostend. It only opened this spring. Ostend is also home to VLIZ, the Flanders Marine Institute. Since my appointment three years ago, I have made collaboration with VLIZ a key priority. The challenges facing the ocean are vast and global. We can only tackle them by sharing knowledge and expertise and working together.”

Is that working?
“Absolutely. We complement each other in several areas. We each have our own expertise, infrastructure and networks. By bringing these together, we can strengthen ocean research and collaboration. VUB aan Zee also provides an excellent base for this.”

And why is 16 November not a coincidence?
“In the same week, from 17 to 20 November, the World Conference of Marine Biodiversity 2026 will take place in Bruges. This gives alumni the opportunity to combine both events.”

Who exactly are these alumni?
“They are alumni of international programmes focusing on marine and freshwater ecosystems, ranging from FAME, MareLac, ECOMAMA, TROPIMUNDO and IMBRSea to Oceans & Lakes. Today, our alumni are active all over the world. We have fairly comprehensive data on the more recent generations, but it is sometimes more difficult to trace older cohorts, particularly those from the 1980s and 1990s. For those, we are also searching archives and reaching out to former contacts.”

Is OceanConnectXL an international community?
“Definitely. Our students come to Belgium from all over the world and, after completing their studies, spread out across the globe again. This creates an international network spanning different generations. Our oldest alumni have built up decades of experience, while younger alumni are still at the start of their careers. Many also retain strong ties with Belgium. Their experience and expertise can add value for younger generations, new research and new collaborations. At the same time, Flanders, and Belgium more broadly, is an internationally important hub of expertise in marine research and ocean management.” 

Does ocean research need to be global?
“Absolutely. The ocean is one interconnected system that extends across national borders. We can draw administrative boundaries, but ecological processes do not respect them. Species do not recognise these boundaries either. Moreover, a large part of the ocean lies beyond national jurisdiction. International cooperation and agreements are therefore essential. With OceanConnectXL, we want to help connect international expertise and experience.”

The warming of the ocean is being felt around the world. What does this mean for these species?
“The ocean is indeed warming. As a result, a number of cold-water species are shifting their distribution towards cooler waters. In the North Sea, this often means a shift northwards. Globally, we are seeing that such shifts can happen rapidly. For some marine species, ranges are shifting by tens of kilometres per decade. As a result, species also find themselves in new communities, changing the interactions between them. This often has unpredictable consequences for how ecosystems function.”

So the North Sea is already becoming too warm for the brown shrimp?
“Results from the VLIZ SeaWatch-B project show that numbers of brown shrimp in shallow coastal waters have declined significantly. Long-term measurements by ILVO covering a wider area do not show a steady decline, but they do show strong year-to-year fluctuations. In any case, ecosystems are under considerable pressure. Cold-water species are coming under threat, while warm-water species are becoming more abundant.”

The arrival of new species does not necessarily mean a net gain?
“No. Many species are declining or disappearing. This also changes the composition and functioning of the ecosystem. So there is indeed a serious impact in a broader ecological sense.”

How else is the North Sea changing as a result of warming?
“Warming is putting further pressure on ecosystems, alongside other human impacts such as intensive fishing and eutrophication. Jellyfish and comb jellies are becoming more common. We are seeing a strong increase in sea gooseberries, a native species, while the American comb jelly, a non-native species, has become established in our waters.”

How do such invasive species get here?
“Among other things, through ships’ ballast water. Whether they can establish themselves here also depends, among other things, on temperature. The warming of the North Sea is changing the composition of our coastal ecosystems and can have knock-on effects throughout the food web.”

Are species also shifting their ranges in the tropics?
“Absolutely. For tropical species, for example, warming can allow them to expand towards higher latitudes. This is known as the tropicalisation of temperate ecosystems. Mangroves are a good example. Along the south-eastern coast of the United States, we are seeing warmer winters facilitating the expansion of mangroves towards higher latitudes, with the transition between mangrove forest and salt marsh also shifting. These shifts do not happen in the same way everywhere. Weather patterns and local conditions also play a role. We study these kinds of shifts through various projects within our research group.”

You have also recently started studying our own mudflats and salt marshes. Apparently, they have a lot in common with tropical mangroves?
“They are different ecosystems, but they do share a number of important characteristics. Both mangroves and mudflats and salt marshes are tidal ecosystems at the interface between land and sea, where water, sediment and vegetation interact. They provide habitats for numerous organisms and can store significant amounts of carbon, particularly in the soil. Mangroves and salt marshes are therefore internationally considered so-called blue carbon ecosystems. These ecosystems also provide other important ecosystem services, such as reducing wave energy and helping to limit coastal erosion and flood risk.”

How exactly does this carbon storage work?
“That is what we aim to find out through the WETCOAST project. We are studying two locations: a new mudflat and salt marsh area developing following depoldering along the Scheldt, and a newly constructed island in the Guayas Delta, where we are monitoring the establishment of mangroves. This allows us to track how much carbon these ecosystems store, how quickly this storage develops and which factors influence it.”

How are you approaching this?
“By combining different measurements. We map carbon in the soil and vegetation and measure carbon fluxes through the atmosphere and water, including the exchange of CO₂ and methane. Using drones, we can scale up these measurements to the landscape level and track changes in vegetation and topography. This gives us a more complete picture of the carbon cycle and helps us better understand how much carbon is stored, how quickly this happens and which factors influence it.”

You can follow these ecosystems from the very beginning, too?
“Yes. In the Hedwige-Prosperpolder and the Guayas Delta, we are there from the very beginning of these ecosystems. They are our living labs: a tidal marsh in a temperate climate and a mangrove system in the tropics. This allows us to investigate how their carbon storage and contribution to coastal protection change as they develop.”

Can we also harness nature to protect ourselves?
“That’s right. But to do so, we also need to understand how these functions develop: how quickly they emerge and which conditions determine them. With this knowledge, we can build a stronger evidence base for nature-based solutions for climate mitigation and adaptation. Research not only helps us understand problems, but also to develop solutions, assess their feasibility and share that knowledge internationally.”

Humanity and nature: one common struggle?
“We often look at humans and nature as if they were two separate systems, whereas our society is itself part of a much larger natural system. We can profoundly alter that system, but we cannot detach ourselves from it. What we do to our environment ultimately comes back to us. We are destroying the self-cleaning and self-regulating functions of the very home we live in.”

How long will the WETCOAST study run?
“Three years. But we hope to continue the research for longer, because long-term research is essential for questions like these.”

Back to the warmer seas for a moment. Will they lead to a wet autumn and winter?
“That could indeed increase the likelihood of heavy rainfall in autumn. This year, we have had an exceptionally warm summer as well as a prolonged marine heatwave. The North Sea cools down only slowly, so it remains relatively warm in autumn. This promotes evaporation, putting more moisture into the atmosphere. When that moist air is subsequently carried inland and cools down, the moisture can condense and fall as precipitation.”

Everything is connected…
“That is a message I always try to convey to my students. As the American naturalist John Muir put it: ‘When we try to pick out anything by itself, we find it hitched to everything else in the universe’. Whatever you look at, it is connected to everything else. I graduated as a physical geographer with a thesis in glaciology, and today I lead projects on tropical coastal ecosystems. At first sight, those subjects could hardly seem further apart. But ultimately, they all take place on the same planet, Carl Sagan’s Pale Blue Dot.”

What do you think when you look out at the sea?
“Panta rhei: everything flows, everything is constantly moving and connected. When I feel a raindrop on my face while standing on the platform at Etterbeek station, I often think about the long journey the molecules making up that drop have already travelled. From the atmosphere to rivers, soils and oceans. For me, there is a profound sense of wonder and humility in that. Water connects ecosystems and people across the world. And that brings us back to the fact that we humans are ourselves part of nature. So it is in our own best interests to take good care of it.”