"The Wadden Sea represents an extraordinarily challenging ecosystem"
Wadden Sea Species Count:
It's tough to provide an exact figure, but approximately 10,000 species call the Wadden Sea home. These include birds, mussels, snails, crabs, and countless others. With thorough exploration, you'll discover even more species in a single handful of sand! Despite its substantial species population, the Wadden Sea can be considered species-sparse due to its status as a relatively recent habitat, formed around 7,000 to 8,000 years ago after the last ice age. Losing its primeval splendor, the Wadden Sea doesn't harbor any endemic species exclusive to its region.
What makes Wadden Sea species unique?
In a nutshell, they're tenacious. The Wadden Sea is infamous for its harsh conditions, with temperatures dipping in winter and soaring in summer. Organisms in the tidal zone must cope with these drastic alterations while being exposed to air twice a day, despite their natural preference for water. Add to this the constant churn caused by wave action, and you have a habitat deserving of extreme praise for the survivors that call it home. Its creatures push against the odds, thriving in an environment that would logically render them extinct.
How has biodiversity in the Wadden Sea evolved over the past 100 years?
A straightforward count of species reveals an increase in their number over time. Many of the species we enjoyed a century ago are still present today. However, human intervention in the form of global trade and aquaculture has introduced foreign species to the Wadden Sea. As a result, the number of foreign species now residing in the Wadden Sea surpasses the number driven to extinction due to human activities like fishing. In the past 100 years, around 100 new species have settled in the Wadden Sea, with the introduction rate remaining consistently high, at roughly two new species each year.
Does this introduction of new species signal good, bad, or a mix of both?
People have an innate tendency to evaluate things based on whether they are considered good or bad. Yet the introduction of new species doesn't always result in negativity. Surprisingly, we haven't discovered any cases of native species being displaced by comparable foreign counterparts. On the contrary, there seems to be ample space for foreign species to coexist with their native counterparts in the Wadden Sea, resulting in a harmonious blend of ecosystems.
How do you account for this observed harmony?
Coasts are dynamic and ever-changing systems, allowing species to shift and adapt according to their needs. Unlike landlocked lakes, which have a clearly defined spatial boundary, coastal ecosystems are much more fluid, enabling species to naturally move and settle in areas suitable for their needs. Additionally, the Wadden Sea isn't yet saturated with species that could potentially hinder the establishment of newcomers. It's similar to a home where vacant rooms await their new inhabitants. Even if every room becomes occupied, nature will find a way to accommodate a few more residents, maintaining a delicately balanced harmony.
The introduction of Pacific oysters to the North Sea in the 1980s for aquaculture purposes was initially met with concern. As it turned out, the oysters were more than capable of reproducing in the colder environment. Despite initial concerns about their impact on native mussel beds, we now know that these two species are living in harmony, each managing to thrive alongside the other.
What allowed for their peaceful coexistence?
Oysters and mussels share the same nutritional requirements, yet their coexistence in the Wadden Sea around Sylt has been remarkably successful. Our research indicates that Mussels actually benefit from the presence of oysters. Birds and crabs, two common predators of mussels, find it more challenging to access the bottom-dwelling mussels in a reef populated with both species. With oysters positioned above the mussels, mussels are now better protected from predation and can survive with smaller overall growth.
Are there any species that have regrettably vanished from the Wadden Sea in the past 100 years?
Unfortunately, yes. Certain species have experienced declines, while others have left the Wadden Sea entirely. In particular, European oysters were once ubiquitous in the Wadden Sea but were heavily fished, leading to their decline and disappearance. The extinction of associated species that lived within these oyster reefs followed suit. Yet neither climate change nor an invasive new species are responsible for this disappearance. Fishing was the culprit here.
Does the natural process of species adaptation and potential extinction adhere to any general patterns or rules?
Change is a natural and necessary part of ecosystems. The Wadden Sea we know today would have appeared quite different 100 years ago if left to its natural evolution. Seasons like harsh winters, intense storms, or a combination of both, trigger new development and ecological patterns that might never have occurred otherwise. Change is an essential aspect of coastal evolution, and unpredictability determines the shape of the North Sea coast in the future.
At what point does this adaptive evolution become challenging?
The significance of a habitat's role cannot be underestimated. Each spring and autumn, millions of birds rely on the Wadden Sea as their feeding ground. After gathering energy here, they either head to their breeding grounds or return to their wintering grounds. Essentially, the Wadden Sea provides nourishment. As long as this provision continues, the birds thrive. However, human interference poses a severe threat to this function, leading to dire consequences. The functions of a habitat are not immune to natural transformations either; change is an inherent part of nature, and there are no assurances of stability.
Recently, I discussed climate change impacts at the Sylt Wadden Sea Station. Among the concerns, the rising sea level has my attention. We've fortified the entire North Sea coast, not just in Germany, but also in the Netherlands and Denmark, using dikes. The Wadden Sea lies between the escalating sea level and these protective barriers, constrained like in a corset. The Wadden Sea can adapt alongside the rising sea level, provided it doesn't surge too rapidly, and provided we allot it necessary space. Unfortunately, this is not happening currently. Future strategies must account for managing the North Sea coast and possibly transitioning to a more adaptive coastal protection governance than what we've known so far, benefiting both humanity and biodiversity.
So, what am I implying?
Consider the altered rivers, which we have channeled and enclosed with dikes. Issues emerging from these waterways can have major consequences. In a similar fashion, if sea level continues to rise before the North Sea coast dike, the same risks materialize. It's like the unstable situation just prior to a dam collapse in the mountains. We can't just eradicate all North Sea coast dikes; there are infrastructure resources to safeguard behind these barriers as well.
What could be a viable solution?
The space between the coastal dike's front and back is growing, and the economic and environmental costs associated with coastal protection over a 100-year period will eventually merit consideration. There is time now to explore feasible and sustainable ideas. These may involve granting the sea a controlled zone, and perhaps other innovative concepts as yet unexplored. Our research at the northern Wadden Sea unites scientists from geology, ecology, and modeling disciplines. Perhaps this case study can serve as a template for other coastal regions, sparking a discourse about sustainable options. Tourists tend to flock to the Wadden Sea during the summer, and with the scorching summers in the south, this number is likely to grow. Consequently, we must deliberate on how we intend to conserve this valuable marine ecosystem in the future. This goal affords prospects that could favor both nature and humanity over the long term.
Christian Buschbaum spoke with Solveig Bach
The Alfred Wegener Institute, known for its significant contributions to marine research, has conducted studies on the Wadden Sea to understand its unique biodiversity. Despite the Wadden Sea being a recently formed habitat, the institute's researchers have discovered that the species living there are highly resilient and adaptable.
The Alfred Wegener Institute is currently working on sustainable solutions to ensure the survival and thriving of the Wadden Sea's unique species in the face of rising sea levels and human interference.
