Droning on in harmony: restoring the giant moss to Basin Head lagoon

Multi-party collaboration and drone-based mapping is enabling ecosystem restoration in the Basin Head Marine Protected Area,   Prince Edward Island. The MPA was established in 2005 to protect a genetically distinct giant... [ view full abstract ]

Multi-party collaboration and drone-based mapping is enabling ecosystem restoration in the Basin Head Marine Protected Area,   Prince Edward Island. The MPA was established in 2005 to protect a genetically distinct giant Irish moss (Chondrus crispus) having an unusual, asexual life history and obligate relationship with mussels. The combined impacts of mussel predation by invasive European green crab (Carcinus maenas) and eutrophication that stimulates Ulva blooms that smother benthic life are believed to have triggered loss of 99.9% of the Irish moss-mussel bed between 1999 and 2014. Research initiated by DFO in 2014 in collaboration with the University of PEI and the Souris and Area Branch of the PEI Wildlife Federation identified threats to Irish moss and mussel populations, which verged on extirpation. The crab population was monitored and methods to stabilize losses and promote re-growth of the Irish moss - mussel bed were devised and tested. Historical harvesting that opened up the bed, ongoing smothering by organic rich silt and eroded saltmarsh debris, shallowing of waters by sediment deposition associated with local land use, and increasing summer high water temperatures were added to the list of threats to ecosystem health but crab predation was deemed the most urgent threat. Drone-based aerial photography was used to develop georeferenced base maps on which Irish moss distribution and movements of moss-mussel clumps over time were mapped. Potential Irish moss habitat was mapped and quantified. Trapping of green crab, augmentation of mussel stock, and planting of Irish moss and eelgrass are ongoing.