The dinghy slowed to a stop at a long line of black bobbing baskets and David Lawlor reached out to inspect the first one.<\/p>\n
Inside lay 60 oysters, all with their shells closed, shielding the life within. \u201cThey look great,\u201d beamed Lawlor. So did their neighbours in the next basket and the ones after that, all down the line of 300 baskets, totalling 18,000 oysters.<\/p>\n
They are, however, never to be eaten. Instead they are tasked with reproducing and restoring oyster reefs to Dublin Bay more than two centuries after they were wiped out. \u201cWe want them to live long and happy lives,\u201d said Lawlor.<\/p>\n
Baskets filled with oysters in D\u00fan Laoghaire harbour in Dublin Bay. Photograph: Rory Carroll\/The Guardian<\/p>\n
This pioneering project in D\u00fan Laoghaire harbour is betting that a species that thrived here for millennia \u2013 before the waters became an oyster graveyard \u2013 can do so again.<\/p>\n
Similar restoration projects are unfolding elsewhere in a continent that once had sprawling reefs <\/a>of the European flat oyster (Ostrea edulis) until overfishing, dredging and pollution wreaked obliteration.<\/p>\n Reefs create rich ecosystems, provide a habitat for almost 200 fish and crustacean species and play a vital role in stabilising shorelines, nutrient cycling and water filtration.<\/p>\n \u201cThese oysters are amazing climate heroes,\u201d said Lawlor, co-founder of Green Ocean Foundation<\/a>, a nonprofit that is driving efforts in Dublin. \u201cThey are natural filter feeders. Each oyster filters at a rate of 190 litres of seawater a day.\u201d<\/p>\n By feeding on plankton and nitrates, the oysters clear algae and help sunlight to reach the seafloor, boosting sea grass \u2013 a carbon sink \u2013 which in turns helps other species and improves coastal biodiversity and marine habitat.<\/p>\n Ireland<\/a>\u2019s inhabitants cultivated oysters in the middle ages but in the 1800s industrialisation and overfishing killed off the Dublin Bay reefs \u2013 a phenomenon replicated from Scandinavia to the Mediterranean.<\/p>\n Inspired in part by New York\u2019s Billion Oyster Project, Lawlor enlisted volunteers and business sponsors for pilot projects that moved oysters from Tralee Bay in County Kerry to sites in Malahide, Howth, Poolbeg and D\u00fan Laoghaire, which ring Dublin bay, and in Greystones, in County Wicklow.<\/p>\n Lawlor inspects oysters laid in Dublin Bay by the Green Ocean Foundation. Photograph: Rory Carroll\/The Guardian<\/p>\n \u201cYou\u2019re building your understanding of why things work well or don\u2019t work well. You want to make sure they survived, to see what the growth was like, and to see if they spawn,\u201d said Lawlor.<\/p>\n The transplanted oysters fared especially well in D\u00fan Laoghaire so it was chosen for the next phase of the project \u2013 last November volunteers placed 300 baskets with 18,000 adult oysters in a sheltered part of the harbour. It is hoped they will become broodstock \u2013 spawn baby oysters in summer that will settle around the harbour and, in time, create a reef.<\/p>\n Scientists from Dublin City University\u2019s Water Institute <\/a>analysed the water last year for baseline indicators and will monitor the oysters\u2019 impact with sensors and chemical and biological assessment.<\/p>\n The baskets are connected along a 100-metre line and are flipped by hand every few weeks to let Arctic terns, gulls and other birds peck away fouling that might otherwise curb the flow of water through the baskets.<\/p>\n In Northern Ireland<\/a>, the charity Ulster Wildlife used a different technique recently to place 2,000 adult oysters and 30,000 juveniles<\/a>, sourced from Scotland, on the Belfast Lough seabed.<\/p>\n Aoibheann Boyle and Andrew Collins inspect oysters at the Green Ocean Foundation\u2019s project in D\u00fan Laoghaire harbour. Photograph: Rory Carroll\/The Guardian<\/p>\n