Oyster Bags

Over the last four decades, the invasive European Green Crab (Carcinus maenas) has made its way northward from California to the coastal waters of British Columbia.  Efforts are underway to better understand the spread of this species and its impacts on the coastal marine environment and native biological communities during adult life stages. Due to knowledge gaps about their early life history, we are using  Oyster Bags to investigate settlement timing of C. maenas – along with that of native crab species – across our coast, and to better understand the impacts they may have on ecological communities during their juvenile life stages.  

What are Oyster Bags?
Oyster Bags are three-dimensional settlement structures that aim to mimic oyster reef habitat and are designed to recruit settling crab larvae and juveniles.  These monitoring structures consist of mesh bags containing oyster cultch (oyster shell) and are deployed both off of docks, as suspended treatments, and in the mid-intertidal, as anchored treatments.  We are using Oyster Bags to examine the potential of oyster shell as a recruitment substrate for various crab species, including C. maenas and the native Dungeness Crab (Metacarcinus magister), settlement patterns of both native and invasive crab species, and species interactions including predation, competition, and avoidance behaviors.