That first touch of the sea, the sand, and the sun in the sky of the Wadden Sea

By Dr. Mansee Bal Bhargava 

Walking on the seafloor is always ecstatic. That first touch of the sea, the sand, and the sun in the sky at Wilhelmshaven’s Wadden Sea was enlightening. Making it a part of everyday life is deeply emotional. Three decades of studying mainland small lakes have now evolved into exploring the world’s largest intertidal transboundary coastal wetland. This leap in the learning curve carries a responsibility, starting with understanding the sea from its smallest drop to its vast expanse. As a beginning, I share a glimpse of the largest unbroken tidal flats system as a co-inhabiting creature among millions, for the coming years.

The Wadden Sea is an intertidal zone in the southeastern North Sea. Formed 7,000–10,000 years ago when glaciers from the last Ice Age melted, rising sea levels filled the North Sea, creating a sandy seawall later breached by sea channels. As peat bogs eroded with further sea-level rise, the Wadden Sea emerged as a vast, dynamic tidal system with a unique coastal ecosystem of salt marshes, tidal flats, and islands.

Today, the Wadden Sea is one of the last large-scale intertidal ecosystems where natural processes function largely undisturbed. The phrase “natural processes continue undisturbed” must be understood from a social-ecological perspective, where human elements—individuals, institutions, and technology—interact with and are governed by the unyielding physical laws of nature.

The Ecology of Ebb and Flow

The Wadden Sea transforms dramatically across seasons and even multiple times daily. At one moment, it is kilometers of vibrant tidal flats teeming with life; at another, a mass of water with restless waves, all driven by the moon and sun’s invisible influence on tides. The mudflats, or seabed, are dry at low tide and submerged at high tide. This rhythmic ebb and flow, coupled with dynamic forces, shapes a unique landscape with unpredictable weather and extreme, often unknown, habitats.

As a shallow waterbody separated from the open sea by low-lying Frisian Islands, it forms a dynamic system of mudflats, sandbanks, and wetlands. Sediments are largely supplied from the adjacent sea. With salinity (20–30 psu) lower than the open ocean (34 psu) but higher than estuaries (0–20 psu), it supports a rich marine habitat. The shallow waters, with sand dunes and mudflats, host over 2,700 marine species, 10,000+ flora and fauna species, 5,100+ semi-terrestrial and terrestrial species, and 10–12 million migratory birds annually, traveling between Canada, Scandinavia, and the Russian Arctic for food and rest. Birds, including geese and avocets, breed in the National Park, with chicks feeding on the seabed at low tide. Tiny crabs, mussels, oysters, seals, and porpoises thrive, making the Wadden Sea a living nursery of marine life critical to global biodiversity.

The Physical-Administrative Ecosystem

The Wadden Sea, a transboundary wetland, stretches over 500 kilometers of coastline from Den Helder in the Netherlands, past Germany’s river estuaries, to Skallingen in Denmark. The term “wad” (Frisian-Dutch for “mud”) is “watt” in German and “vade” in Danish. Covering nearly 11,500 square kilometers, this temperate, flat coastal wetland is shaped by intricate physical and biological interactions, forming diverse habitats like tidal channels, sandy shoals, seagrass meadows, mussel beds, sandbars, mudflats, salt marshes, estuaries, beaches, and dunes/islands.

Its transboundary nature fosters collective action among Denmark, Germany, and the Netherlands. Since 1978, these countries have collaborated under the Trilateral Wadden Sea Cooperation (TWSC), guided by the principle of achieving “a natural and sustainable ecosystem in which natural processes proceed in an undisturbed way.” The TWSC protects the Wadden Sea as a single ecological entity, driven by the need for coordinated transnational management. This cooperation, initiated due to declining harbor seals, the region’s importance for migratory birds, and threats like climate change, shipping, and fishing, was formalized in the 1982 “Joint Declaration on the Protection of the Wadden Sea” (updated 2010). This declaration outlines objectives, institutional, and financial arrangements, fostering collaboration across politics, conservation, science, administration, and local stakeholders. In a world of rising transboundary water conflicts, the TWSC offers a model for cooperation.

This collaboration led to the Wadden Sea’s inscription as a UNESCO World Natural Heritage Site (Biosphere Reserve, Site Id: 1314) in 2009, recognized for its dynamic geological processes, biodiversity, migratory bird significance, and effective trilateral management. It encompasses the Dutch Wadden Sea Conservation Area, German Wadden Sea National Parks of Lower Saxony and Schleswig-Holstein, and the Danish Wadden Sea maritime conservation area. In the EU, it is designated under Natura 2000 as a Special Area of Conservation (SAC) for non-bird species/habitats and a Special Protection Area (SPA) for bird species. Since 2015, it is also a Transboundary Ramsar Site, including 13 Ramsar Sites across the three countries, covering about 60% of the northeastern Atlantic’s intertidal shores.

The Human Interface and Emerging Threats

The Wadden Sea’s rich ecosystem supports a vibrant cultural heritage and complex economic activities. Tourism and recreation, focused on ecotourism and nature-based activities like tidal flat hiking, island tours, and cycling, attract millions of visitors, generating billions of euros (approximately €7 billion direct and indirect) and supporting around 60,000 jobs. The UNESCO designation has boosted ecotourism, but efforts like the Wadden Sea Tourism Radar aim to balance tourism with conservation to protect biodiversity and local infrastructure. Fishing, a key microeconomic activity, faces management challenges. Macroeconomic activities—shipping, ports, pipelines, offshore energy, and resource extraction—conflict with conservation, causing habitat loss, wildlife disturbance, and pollution.

Climate change severely impacts the Wadden Sea. Rising sea levels threaten salt marshes and islands with inundation, as sedimentation lags behind. Warming oceans introduce southern warm-water species, disrupting native species’ life cycles and ecosystem balance. Historical salt extraction, causing land subsidence, and restrictions on salt projects due to tidal flat damage further limit salt marsh expansion.

Way Forward

Safeguarding the Wadden Sea, particularly for birds, began a century ago. The TWSC’s “Joint Declaration” unified the three countries’ conservation and management plans, aligning national policies. The “Wadden Sea Network” and “Wadden Sea Forum,” comprising diverse stakeholders, are supported by the Trilateral Wadden Sea Secretariat and ministries. As the TWSC approaches its 50th anniversary in 2028, reflecting on its achievements and challenges is crucial to chart the Wadden Sea’s future. “Quality Status Reports” (QSR) indicate relative stability compared to other biodiversity hotspots, likely due to robust laws, management, and global awareness. The Wadden Sea’s conservation model offers lessons in cooperation, conservation, and peace for wetlands worldwide.

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Dr. Mansee Bal Bhargava is an entrepreneur, researcher, educator, speaker, and mentor. She recently joined the Carl von Ossietzky University of Oldenburg at the Institute for Chemistry and Biology of the Sea (ICBM) in Wilhelmshaven as a Senior Scientist to lead the Trilateral Research Project WADCouple. More about her work at: www.mansee.in, www.edc.org.in, www.wforw.in, www.woder.org