A first record of intertidal Ostrea edulis 3D structural matrices in Strangford Lough Northern Ireland - An emergent reef?

Abstract

The European flat oyster Ostrea edulis once settled in high densities throughout its natural range but now exists only in small fragmented populations. In the Sea Lough of Strangford, Northern Ireland, recent increases in intertidal oyster numbers at historical sites along the north-east shore were recorded in 2018. A substantial number of conjoined oyster settlements were recorded within this density increase. One intertidal site produced numerous three-dimensional (3D) O. edulis specific matrices containing > 16 oysters. In contrast, an extensive search of post and pre-1700s literature uncovered relatively few accounts of species-specific 3D O. edulis matrices and none relating to intertidal populations. The gregarious 3D settlements discovered during this research represent the first documented evidence of the phenomenon in Ireland. These emergent native oyster reef structures offer an insight into the possible intertidal O. edulis formations, which existed pre-1700 and could act as a guide to what may still be obtainable in the future.

Population dynamics of the European native oyster in a Marine Conservation Zone exposed to unregulated harvesting

“…This resulted in a dramatic decrease in O. edulis numbers over a short three-year period in the 2000s (Roberts et al, 2005) reminiscent of the excessive exploitation of the 1800s indicating that personal consumption limits were not being adhered too. Indeed, subsequent surveys in the 2010 s have shown small increases in oyster numbers at sites until they reach a commercial size (Kregting et al, 2020). However, the removal of these marketable size cohorts has been recorded for over a decade on low spring tides when shellfish gatherers have had easy access to the oysters (Smyth et al, 2020).…”