The reefs, which covered over 1.7 million hectares of Europe’s seafloor, created habitats for almost 200 species of fish and crustaceans, while playing a crucial role in shoreline stabilization, nutrient cycling, and water filtration.
Once abundant across Europe’s coastlines, oyster reefs were vibrant ecosystems that supported a wide range of marine life, but over a century of human activity has led to their near extinction, as revealed in a new study. Published in Nature Sustainability, this research showcases the historic significance of the European flat oyster (Ostrea edulis), which created complex underwater structures that spanned from Norway to the Mediterranean.
The Loss of Marine Biodiversity
The study, based on historical records from the 18th and 19th centuries, shows that these reefs were once composed of millions of living oysters piled upon the shells of their predecessors. The reefs, which covered over 1.7 million hectares of Europe’s seafloor, created habitats for almost 200 species of fish and crustaceans, while playing a crucial role in shoreline stabilization, nutrient cycling, and water filtration. Yet, by the early 20th century, overfishing and other human impacts had destroyed these ecosystems.
Today, only scattered populations of flat oysters remain, but the complex reefs they once built have been erased from much of Europe’s coastal waters. “Few people today would recognize what our oceans once looked like,” says Dr. Ruth Thurstan from the University of Exeter. “The vibrant, three-dimensional landscapes created by oyster reefs are gone from collective memory, replaced by the image of a flat, muddy seabed.”
A Glimmer of Hope for Restoration
Restoration projects, such as The Wild Oyster Project led by ZSL and its partners, aim to bring back these vital habitats on a small scale. However, researchers emphasize that more needs to be done if oyster reefs are to thrive once again across Europe. With support from governments and policymakers, large-scale restoration efforts could help restore these once-vital ecosystems, improving biodiversity and marine health along Europe’s coasts.
By combining historical accounts from newspapers, travel writings, and interviews with fishermen, researchers have pieced together a clearer picture of Europe’s lost marine habitats. The Convex Seascape Survey, a five-year initiative exploring ocean carbon storage, has also contributed to understanding the extent of these lost reefs. “Historical data helps us imagine what our seas used to look like,” says Dr. Thurstan. “It’s crucial information if we are to make any meaningful progress in conserving and restoring what’s left of these ecosystems.”
Rebuilding What Was Lost
The destruction of oyster reefs through overfishing caused a dramatic shift in marine biodiversity, flattening the seabed and leaving behind an expanse of soft sediment. According to Dr. Philine zu Ermgassen of the University of Edinburgh, “Oyster reefs are slow to grow but were destroyed quickly, fundamentally altering the structure of our seafloor.”
The challenge now lies in reversing these effects. Over 30 researchers from the Native Oyster Restoration Alliance are calling for increased restoration efforts, working across Europe to revive these critical ecosystems. Though it will take time, the potential benefits of restored oyster reefs—ranging from improved biodiversity to cleaner coastal waters—make the effort worthwhile.
