A study by an Atlantic Technological University (ATU ) researcher has been spotlighted in the December issue of the BBC Wildlife Magazine, bringing attention to the critical state of Europe’s native oyster reef ecosystems.
Dr José M. Farinas-Franco, a marine ecologist at ATU, co-authored the paper “European Native Oyster Reef Ecosystems Are Universally Collapsed” published in the well-known journal, Conservation Letters. Alongside this, photographs of one of the last areas of known native oyster habitat, located off the West Coast of Ireland, captured by Dr Farinas-Franco were featured in the ‘Discover Wildlife’ article, offering a visual glimpse into one of the last remnants of these vital habitats.
The study revealed that the once-thriving native oyster reefs across Europe have now been classified as ‘collapsed’ under the International Union for Conservation of Nature’s (IUCN ) Red List of Ecosystems criteria. Historically, these reefs spanned vast areas, including a now-destroyed 20-mile-long reef off the coast of Arklow, Ireland. However, modern-day assessments show that no remaining habitat exceeds 0.1 hectares in size.
Current research carried out at ATU, led by Dr Jose M. Farinas-Franco, discovered small pockets of native oyster reef habitats on the west coast of Ireland that can be used as a reference to guide the restoration of oyster reef ecosystems to what they once were. This work, while confirming the absolute degradation caused by human activities to this critical marine ecosystem in Europe, also highlights the need for protecting remnant oyster reefs and the potential benefits of investing in large-scale and more ambitious ecosystem recovery projects.
Dr Jose M. Farinas-Franco, said, “After an in-depth review of historical records from across Europe, including Ireland, we found that native oysters created extensive reefs with dense aggregations of oysters and high biodiversity. For example, 19th-century sources report the presence of a now-destroyed oyster reef off Arklow extending 20 miles in length and four miles in width.
“The research found there are no locations remaining in Europe where the habitat (high densities of oysters ) extends beyond 0.1ha, and we conclude the ecosystem has collapsed. While there are many policies in place to manage oyster beds these are purely fisheries oriented in its vast majority of their range (including Ireland ) embracing a highly shifted baseline even if they consider oyster beds an ecosystem.”
Vital habitats
Described as ‘complex and three-dimensional’, historic oyster reefs once grew to the size of a football pitch, collectively covering an area of more than 1.7 million hectares. These gargantuan reefs once hosted a ‘diverse, abundant and flourishing community of fish, crabs, starfish and birds’. In addition to this, oyster reefs also provide food for people, stabilise shorelines, cycle nutrients, and filter water, with a single adult oyster filtering up to 200 litres of water daily.
Primarily due to historical overexploitation compounded by poor water quality and disease, the seafloor is now a flat, barren expanse of sediment with low diversity. European oyster reef habitats are now so scattered and degraded that, except for a few locations such as Norway and Sweden, oysters are largely found in isolation or tiny clumps. In Europe, most oyster populations exist in densities of less than one individual per square meter. Where they are found grouped, these oyster clumps cover less than 0.1ha.
The publication of this research comes at a pivotal moment as international initiatives, such as the EU Nature Restoration Law, aim to reverse biodiversity loss by restoring degraded ecosystems. Dr. Farinas-Franco’s findings emphasize the importance of including oyster reefs in these efforts and investing in innovative, large-scale restoration projects.
The decline of European Native Oyster ecosystems highlights a crucial moment for marine biodiversity. Human activities have drastically altered these habitats, leading to isolated oyster populations. Restoration efforts must recognise oysters’ ecological importance and adopt a holistic approach to revitalising marine environments.
