Native Oyster Reef Restoration Ireland


Native Oyster Reef Restoration Ireland (NORRI)

Globally, oyster habitats (reefs) are the most degraded habitats among coastal systems, with the loss of 99% in the last 150 years. These 500 million years old keystone species and their natural keystone habitats are at the brink of a total collapse due to intensive human industrial harvesting and pollution.

Ostrea edulis (native flat oyster) historically embraced and provided numerous ecological functions along the east and southeast coastline of Ireland, establishing 80 km of extensive reefs from Wicklow Head to Ravens Point. Arklow was the main port for oyster fisheries in the 1800s, with a harvest of 40 million oysters in 1863, while today the whole of Ireland lands about 2.1 million native oysters per year.

The local community started the initiative to restore their historic beds and established the Native Oyster Reef Restoration Ireland (NORRI), supported by Wicklow County Council. The first restoration goal is to identify suitable site for oyster reef restoration, along the Wicklow’s coastal marine area, and establish it as a no-take Biomimicry LivingLabs®️ that can be replicated throughout Ireland and Europe. Here is the link to NORRI documentary.

Our solution for oyster habitat restoration uses six biomimicry principles: evolve to survive, adapt to changing conditions, be locally attuned and responsive, resource efficient, use life-friendly chemistry, and integrate development with growth. The environment sets the limits for sustainable and resilient development and restoration, so our premise is to work with nature to help establish conditions conducive to life and help restore native oyster reef habitats, while improving water quality, marine biodiversity and help heal our environment.

THE FIRST ON-LINE NORRI WORKSHOP (31 MARCH 2020)  Watch the workshop video here.

Agenda: A) Introduction to the first oyster restoration project in County Wicklow; B) Oyster sourcing for this project and non-invasive technologies for disease detection; C) Industry participation and stakeholder collaboration;

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Key discussion questions: 1. Addressing the need for integrated coastal habitat restoration, e.g. restoring kelp and oysters in NORRI project; 2. Oyster source/seed for NORRI project and how to make sure the oysters are healthy when moving them to the project restoration site; 3. Funding opportunities, collaborating and learning from each other’s efforts through NORA, and Native Oyster Network UK&Ireland

Native Oyster


Oysters diversified into hundreds of species adapted to specific coastal marine and estuarine environments, becoming one of the most amazing coastal engineers, embracing coasts of every continent. Historically, oyster reefs were capable of spanning several hectares in area and could reach 4-7 meters in height. Oyster reefs are formed through the gregarious settlement of oysters, preferably on their own shells or any other calcium carbonate substrate, which creates three-dimensional structures promoting many important ecological services. As ecosystem engineers, oyster reefs help facilitate ecosystem-wide biodiversity; enhance benthic and pelagic coupling by harbouring of juvenile and smaller fish species; they create natural coastal buffer zones absorbing wave energy and protecting from erosion. Oysters provide excellent water filtration removing nitrogen bound in phytoplankton and organic particulates, as well as promoting bio-deposition, bioremediation, while their shells have pH buffering capacity. 

An adult oyster can filter between 100 and 240 l of water per day and have been observed to remove as much as 0.52 g of N and 0.16 g P at harvest. Similarly, oyster filtration can help reduce the turbidity and improve photosynthesis in deeper waters, promoting the growth of submerged aquatic vegetation (SAV). This very important symbiotic relationship between oyster habitats and SAV like kelp and eel grass beds, have been supporting synergistic ecosystem benefits such as sediment stabilization, habitat creation, coastal protection and improved water quality. In addition, towards the coastal land side oysters prefer the vicinities of salt marshes. Together these three keystone coastal systems act in unison creating some of the most biologically productive areas promoting the overall ecosystem health and function in coastal systems and estuaries. 

Example - Biomimetic Oyster Habitat Restoration in Wellfleet Harbor, MA, USA. Low tide Images: A. Frankic


Biomimetic Restoration Solution

Oyster reef restoration projects have been focused more on reversing the trend of inhibited areas than on rebuilding self-sustaining reefs to promote ecosystem health, functions and services. Oyster population dynamic, carrying capacity and ecological services in any given location depends on that location’s environmental conditions. For example, we had to provide a natural hard benthic substrates (cultch) to support naturally present oyster settlement (Wellfleet Harbor, Chesapeake Bay). However, in the areas where there is a limited or no existing oyster population, restoration was supported by the ‘spat on shell’ approach (Boston Harbor, Nantucket Island, Orleans Harbor). In addition, floating structures were used in the areas where benthic substrate was unsuitable (mucky), made from various materials (recyclable plastic, green cement). Type of environmentally friendly materials (based on Green Chemistry technologies) that we identified to be the most suitable to support oyster reef restoration include various green cements manufactured by BluePlanet Ltd, ECOncrete, and Growoysterreefs.

How many oysters are necessary to support healthy population and reef habitat? Based on the literature review, native reefs consisted of 5,895 oysters per square yard (Luntz, 1960). Therefore, we used this number to visualize and calculate the potential vast of oyster population, density and biomass, as well as carrying capacity in restored areas. For example, in the Wellfleet Harbor project, we established a two acre pilot site and in two years restored 6 million oysters, by placing tons of recycled shells (cultch) for oyster settlement. Restored population of oysters improved the local water quality in the harbor, the biodiversity, including fish and crustacean species, as well as improved sediment quality, and shoreline protection ( How would nature restore oyster reefs?

Oysters have been an essential part of global coastal ecosystems and natural source of flux and nexus of food, water and energy between land and ocean. Biomimicking natural solutions is the most environmentally, economically and socially justified approach. A biomimicry-based approach to oyster habitat restoration will seek to ensure that infrastructures and activities are based on the six core principles: 

1) Does the new restored habitat (structure) have the capacity to evolve and survive? The goal is for the restored oyster communities to become self-sustaining in situ, evolving naturally, providing ecosystem services and functions. 

2) Is the restoration project resource efficient? The multifunctional design in oyster reef restoration uses a water-energy-food nexus process, established between the building structure, surrounding water, benthic communities, and other coastal habitats like salt marsh, kelp and SAV. 

3) How does the restored site adapt to changing conditions and model resilience? Resiliency of habitats and ecosystems attributes to their interconnectedness and interdependence, as living things adapt and evolve locally without waste of energy or materials. Collaboration is the driving force in evolution, not the competition.

4) Are development and growth integrated in the restoration process? Structural designs of oyster habitats are modular and nested within the water column and benthos, over time they integrate development and growth to self-organize to develop complex food webs and trophic interactions. 

5) How is the restoration locally attuned and responsive? The complex ecological functions provided by an oyster reef at the restoration site will need to be determined and incorporated in designing the coastal and marine built structures. 

6) Does the restoration use life-friendly materials, water based chemistry and self-assembly? This principle requires that structures are built by local, natural, untreated materials, sustainable, recyclable, not harmful to water and support conditions conducive to life. 

Adequate, healthy water quality is the most important factor supporting coastal habitats’ health, function and biodiversity. There are numerous missing ecosystem functions and services that oyster reefs can provide in polluted and degraded marine ecosystems, including bioremediation, specifically when addressing the impact and exposure to microplastic contamination and many infectious diseases that limit restoration efforts in marine environments.


Key References

Farinas-Franco, J.M. et al (2018). Missing native oyster (Ostrea edulis L.) beds in a European Marine Protected Area: Should there be a widespread restorative management? Biol.Conserv. Vol. 221, pp. 293-311.

Frankic, A. (2015). Oyster Reef Restoration Project 2011-2014.Town of Wellfleet, Cape Cod, USA. USDA Report.

Frankic, A. et al (2011). Teaching and learning with nature using a biomimicry based approach to restore three keystone habitats: salt marsh, eelgrass, and oyster beds. Proceedings of the first biomimicry in higher education webinar. January 29, 2011: TBI. 

Hargis, W. J., & D.S. Haven. (1999). Chesapeake Oyster Reefs, Their Importance, Destruction and Guidelines for Restoring them. In: Oyster Reef Habitat Restoration: A synopsis and synthesis of approaches. Edited by M.W. Luckenbach, R. Mann and J.A. Wesson. 1999. VIMS Press, Gloucester Pt. VA, USA.

Lunz, G.R., Jr. (1960). Intertidal Oysters. Wards Natl. Sci. Bull. 34(1): 3-7.

Meyl, K. (2001). Scalar waves: Theory and Experiments,1.15.

NORA (2017). Native oyster restoration in Europe – current activities and future perspectives. Kick-off Workshop Berlin, Nov. 1-3, 2017.

Rees, J. (2008). The fisheries of Arklow 1800-1950. Four Courts Press Ltd.

Senga, D.G. (2016). Effects of microplastics on European flat oysters, Ostrea edulis and their associated benthic communities. Env. Pollution, Vol. 216, pp. 95-103.

Shelamoff, V. et al. (2019). Ecosystem engineering by a canopy-forming kelp facilitates the recruitment of native oysters. Restoration Ecology. 10.1111/rec.1301

Tesla, N. (1905). Art of transmitting electrical energy through the natural mediums, USPatent No. 787,412, N.Y. 18.4.1905.

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