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Thousands of oysters are being re-introduced to Dublin Bay as nature's super water cleaners
For over 200 years, native oysters (Ostrea edulis) have been absent in Dublin Bay. Once abundant along the Irish coast, they thrived in the sheltered estuaries and tidal flats that shaped the city's maritime life. Historical records from the 18th and early 19th centuries describe vast oyster beds stretching across the bay. They were a vital food source, a cornerstone of coastal trade and a symbol of Dublin's connection to the sea. By the mid-1800s, however, the beds had collapsed.
A combination of overfishing, industrial pollution, development, habitat destruction, and disease decimated the population. It left behind only fragments of shell in the sediment as traces of what had once been a thriving marine ecosystem. Oyster fishing along the Irish south-east coast is well documented. While oyster cultivation, breeding and growing oysters in Ireland dates back to the 13th century, consumption of oysters here has been a tradition for more than 4,000 years. The widespread disappearance of oyster beds mirrored a broader story—the loss of ecological richness that accompanied urban expansion and industrialization.
Now, through collaborative efforts led by the Green Ocean Foundation, a not-for-profit marine environmental organization, as well as local volunteers and the Dublin City University Water Institute, the oyster is making a return. The reintroduction of oysters to Dublin Bay represents more than ecological restoration—it's a revival of cultural heritage and collective memory.
In November 2025, more than 18,000 oysters have returned to the bay as part of a project that goes far beyond species reintroduction. Housed in 300 floating flip baskets, these oysters will breed future generations.
The baskets are connected along a 100-meter line and are flipped at monthly or bi-weekly intervals (depending on the season), and are in a sheltered area of Dun Laoghaire harbor. David Lawlor, co-founder of Green Ocean Foundation, said that the flipping technique allowed birdlife to remove fouling that could otherwise restrict the flow of seawater through the baskets. Overall, this project is showing how oysters can deliver significant benefits for our coasts and environment.
Each new bed seeded in the bay has the potential to restore not just biodiversity. By building a scientifically supported re-introduction project—it can also provide the proof needed that even the most degraded environments can heal when science, policy, and community unite behind a shared vision.
Oysters are nature's quiet custodians. Each one can filter up to 200 liters of water a day, drawing in microscopic algae, sediments and pollutants, and potentially releasing cleaner water back into their surroundings.
When established, an oyster reef functions like a natural water treatment plant, a living system that not only purifies but also stabilizes shorelines, creates habitat for marine life, and buffers against the impacts of coastal erosion.
Researchers are aiming to restore and reimagine the role of the oyster. DCU's work combines field monitoring, in-situ sensors, chemical analysis and biological assessment to understand how oysters grow and survive under fluctuating environmental pressures, including pharmaceuticals, pesticides, legacy pollutants and microplastics.
Thousands of oysters are being re-introduced to Dublin Bay as nature's super water cleaners
Costa Rica's rainforest reborn by butterflies
I walk towards a wooden gate marked Pierella Ecological Garden and pause. Tucked away in the town of Sarapiquí, Costa Rica, this private rainforest reserve isn't mentioned in many guidebooks, but it's home to one of Costa Rica's most unforgettable experiences.
Once a barren cattle pasture, this small family-run lodge is now surrounded by a regenerated rainforest. Pierella's owners, William Camacho and Kristal Barrantes, have spent the last three decades planting native trees and plants – and it is one of the few places in the world practicing butterfly-led rewilding. Dozens of butterfly species are raised and released here, helping to pollinate plants, disperse seeds and kick-start the complex dynamics a healthy forest needs. As the vegetation has slowly returned, so too have the birds, frogs, reptiles, monkeys and ocelots that now move through the forest.
In a country full of luxury eco-lodges, this off-the-beaten-path destination feels different. Guests stay and eat with the family, and the experience is deeply personal. It's rewilding with a human touch – an example of how tourism, when rooted in reciprocity, can help nature heal.
At the gate, I am invited in by a chorus of bird calls coming from the red ginger plants and cecropia trees. I walk a few steps along a path leading into an open-air kitchen and dining area where Kristal Barrantes, who manages the property, smiles and offers me a homemade dessert. After finishing it, Gerald Barrantes (Kristal's nephew), lifts a spotting scope used for birdwatching and grins. "Ready for an adventure?"
Under the dense, green canopy, Gerald whispers, "Come look at this." I lean in over a broad leaf where a red-eyed tree frog blinks back at us – lime-green skin, crimson eyes, blue-striped legs and tiny orange toes that seem to glow. Just beyond, a toucan with a yellow throat and a reddish band across its chest tears into a banana with its long, two-toned beak.
"Now look through the spotting scope," Gerald says, adjusting the tripod. Through the lens, I spot a majestic turkey vulture, its small red head vivid against the pale blue sky. Gerald explains that these birds live far from human settlements, deep in the wild. High in the trees, a sloth naps lazily, its brown fur blending perfectly with the branches.
Gerald keeps pointing out new creatures, one after another. He explains that in total, more than 200 bird species live in this four-hectare forest, along with monkeys, sloths, iguanas, bats, ocelots and countless frogs and insects. Cacao grows along the paths as well, and visitors can join a hands-on chocolate workshop.
It's hard to believe that this thriving rainforest was once a sun-bleached field.
"In 1995, Pierella was nothing but grassland – just cows and fences," says Gerald, as we hike through the property's narrow dirt trails.
Camacho wanted to restore what had once been rainforest. He had always loved butterflies and saw them as a way to bring life back to the land. Using his savings, he bought a 20m x 20m plot of pasture, planted host trees for butterflies and created a small, sustainable butterfly farm in partnerships with the Costa Rican Entomological Supply, selling chrysalises to butterfly houses and zoos around the world.
Over the past 30 years, he has steadily reinvested the income from his butterflies to purchase neighbouring farmland, transforming the once-barren grazing area into the lush rainforest that stands today. Camacho became one of the first butterfly breeders in Costa Rica to adopt sustainable methods, and farmers across the nation who once cleared trees now visit the property to learn how eco-tourism can replace livestock income.
Gerald soon leads me towards a mesh-covered area. Inside the butterfly tent, called the Butterfly Garden, hundreds of butterflies in a kaleidoscope of colours flutter around me – so many it feels as if I've stepped into a different world.
"We planted for butterflies – the birds did the rest," Camacho says to me, as the insects fly around him. "The butterflies attracted birds; the birds dropped seeds; and the seeds became forest," he says.
Costa Rica has quietly become the world's leading exporter of live butterflies, shipping nearly half a million pupae each year to exhibitions around the globe.
Camacho explained that at Pierella, butterflies sit at the heart of the restoration process. As they feed and lay eggs, they pollinate plants and draw insect-eating birds and reptiles into regenerating areas. Their presence helps rebuild the food web from the bottom up – creating the conditions that allow frogs, bats, snakes and small mammals to return.
At an open-air lab, Gerald stands by a blackboard, explaining how Costa Rica's total forest cover fell from 75% in 1940 to just 21% by 1987. Thanks to nationwide reforestation and eco-tourism efforts, he says the nation's forests have since rebounded to roughly 60%. Behind him, rows of chrysalides gleam like polished jade. Gerald lifts one delicately, showing how different caterpillars harden and shift colour. I witness the moment a caterpillar begins to turn green from the centre of its head, hardening into a chrysalis – a silent metamorphosis taking place before my eyes.
The forest transforms at after dark. Sound replaces sight – frogs trill, wings brush against leaves and a faint patter of rain falls through the canopy. Flashlights reveal leaf-cutting ants marching in long lines holding green blades above their heads, strawberry poison dart frogs, a coiled snake and a green basilisk.
As we move farther along the trail, Gerald pauses beside a broad heliconia leaf. "Look from below," he says. I crouch down and peer inside. A family of Honduran white bats cluster beneath the leaf, their white fur shining in the beam. I didn't know that white bats even existed and I'm utterly thrilled.
In the early morning, the low call of monkeys somewhere beyond the trees wakes me. For a moment, I just listen to birds calling, insects buzzing, unseen creatures stirring the leaves. I make my way to the dining area, where white-necked Jacobin hummingbirds sip from feeders. Nearby, dazzling green honeycreepers dart between branches. Shining honeycreepers, their bodies a vivid cobalt blue striped with black, flash through the trees.
Around them, countless other brilliantly coloured birds I've never seen before gather to feast on ripe bananas. I sip a cup of freshly brewed coffee, listening to the layered morning chorus. It's hard to believe this entire world began with a single idea: that planting for butterflies could one day bring back the jungle. A small act that has sparked big consequences – a true butterfly effect.
Costa Rica's rainforest reborn by butterflies
For over 200 years, native oysters (Ostrea edulis) have been absent in Dublin Bay. Once abundant along the Irish coast, they thrived in the sheltered estuaries and tidal flats that shaped the city's maritime life. Historical records from the 18th and early 19th centuries describe vast oyster beds stretching across the bay. They were a vital food source, a cornerstone of coastal trade and a symbol of Dublin's connection to the sea. By the mid-1800s, however, the beds had collapsed.
A combination of overfishing, industrial pollution, development, habitat destruction, and disease decimated the population. It left behind only fragments of shell in the sediment as traces of what had once been a thriving marine ecosystem. Oyster fishing along the Irish south-east coast is well documented. While oyster cultivation, breeding and growing oysters in Ireland dates back to the 13th century, consumption of oysters here has been a tradition for more than 4,000 years. The widespread disappearance of oyster beds mirrored a broader story—the loss of ecological richness that accompanied urban expansion and industrialization.
Now, through collaborative efforts led by the Green Ocean Foundation, a not-for-profit marine environmental organization, as well as local volunteers and the Dublin City University Water Institute, the oyster is making a return. The reintroduction of oysters to Dublin Bay represents more than ecological restoration—it's a revival of cultural heritage and collective memory.
In November 2025, more than 18,000 oysters have returned to the bay as part of a project that goes far beyond species reintroduction. Housed in 300 floating flip baskets, these oysters will breed future generations.
The baskets are connected along a 100-meter line and are flipped at monthly or bi-weekly intervals (depending on the season), and are in a sheltered area of Dun Laoghaire harbor. David Lawlor, co-founder of Green Ocean Foundation, said that the flipping technique allowed birdlife to remove fouling that could otherwise restrict the flow of seawater through the baskets. Overall, this project is showing how oysters can deliver significant benefits for our coasts and environment.
Each new bed seeded in the bay has the potential to restore not just biodiversity. By building a scientifically supported re-introduction project—it can also provide the proof needed that even the most degraded environments can heal when science, policy, and community unite behind a shared vision.
Oysters are nature's quiet custodians. Each one can filter up to 200 liters of water a day, drawing in microscopic algae, sediments and pollutants, and potentially releasing cleaner water back into their surroundings.
When established, an oyster reef functions like a natural water treatment plant, a living system that not only purifies but also stabilizes shorelines, creates habitat for marine life, and buffers against the impacts of coastal erosion.
Researchers are aiming to restore and reimagine the role of the oyster. DCU's work combines field monitoring, in-situ sensors, chemical analysis and biological assessment to understand how oysters grow and survive under fluctuating environmental pressures, including pharmaceuticals, pesticides, legacy pollutants and microplastics.
Thousands of oysters are being re-introduced to Dublin Bay as nature's super water cleaners
Costa Rica's rainforest reborn by butterflies
I walk towards a wooden gate marked Pierella Ecological Garden and pause. Tucked away in the town of Sarapiquí, Costa Rica, this private rainforest reserve isn't mentioned in many guidebooks, but it's home to one of Costa Rica's most unforgettable experiences.
Once a barren cattle pasture, this small family-run lodge is now surrounded by a regenerated rainforest. Pierella's owners, William Camacho and Kristal Barrantes, have spent the last three decades planting native trees and plants – and it is one of the few places in the world practicing butterfly-led rewilding. Dozens of butterfly species are raised and released here, helping to pollinate plants, disperse seeds and kick-start the complex dynamics a healthy forest needs. As the vegetation has slowly returned, so too have the birds, frogs, reptiles, monkeys and ocelots that now move through the forest.
In a country full of luxury eco-lodges, this off-the-beaten-path destination feels different. Guests stay and eat with the family, and the experience is deeply personal. It's rewilding with a human touch – an example of how tourism, when rooted in reciprocity, can help nature heal.
At the gate, I am invited in by a chorus of bird calls coming from the red ginger plants and cecropia trees. I walk a few steps along a path leading into an open-air kitchen and dining area where Kristal Barrantes, who manages the property, smiles and offers me a homemade dessert. After finishing it, Gerald Barrantes (Kristal's nephew), lifts a spotting scope used for birdwatching and grins. "Ready for an adventure?"
Under the dense, green canopy, Gerald whispers, "Come look at this." I lean in over a broad leaf where a red-eyed tree frog blinks back at us – lime-green skin, crimson eyes, blue-striped legs and tiny orange toes that seem to glow. Just beyond, a toucan with a yellow throat and a reddish band across its chest tears into a banana with its long, two-toned beak.
"Now look through the spotting scope," Gerald says, adjusting the tripod. Through the lens, I spot a majestic turkey vulture, its small red head vivid against the pale blue sky. Gerald explains that these birds live far from human settlements, deep in the wild. High in the trees, a sloth naps lazily, its brown fur blending perfectly with the branches.
Gerald keeps pointing out new creatures, one after another. He explains that in total, more than 200 bird species live in this four-hectare forest, along with monkeys, sloths, iguanas, bats, ocelots and countless frogs and insects. Cacao grows along the paths as well, and visitors can join a hands-on chocolate workshop.
It's hard to believe that this thriving rainforest was once a sun-bleached field.
"In 1995, Pierella was nothing but grassland – just cows and fences," says Gerald, as we hike through the property's narrow dirt trails.
Camacho wanted to restore what had once been rainforest. He had always loved butterflies and saw them as a way to bring life back to the land. Using his savings, he bought a 20m x 20m plot of pasture, planted host trees for butterflies and created a small, sustainable butterfly farm in partnerships with the Costa Rican Entomological Supply, selling chrysalises to butterfly houses and zoos around the world.
Over the past 30 years, he has steadily reinvested the income from his butterflies to purchase neighbouring farmland, transforming the once-barren grazing area into the lush rainforest that stands today. Camacho became one of the first butterfly breeders in Costa Rica to adopt sustainable methods, and farmers across the nation who once cleared trees now visit the property to learn how eco-tourism can replace livestock income.
Gerald soon leads me towards a mesh-covered area. Inside the butterfly tent, called the Butterfly Garden, hundreds of butterflies in a kaleidoscope of colours flutter around me – so many it feels as if I've stepped into a different world.
"We planted for butterflies – the birds did the rest," Camacho says to me, as the insects fly around him. "The butterflies attracted birds; the birds dropped seeds; and the seeds became forest," he says.
Costa Rica has quietly become the world's leading exporter of live butterflies, shipping nearly half a million pupae each year to exhibitions around the globe.
Camacho explained that at Pierella, butterflies sit at the heart of the restoration process. As they feed and lay eggs, they pollinate plants and draw insect-eating birds and reptiles into regenerating areas. Their presence helps rebuild the food web from the bottom up – creating the conditions that allow frogs, bats, snakes and small mammals to return.
At an open-air lab, Gerald stands by a blackboard, explaining how Costa Rica's total forest cover fell from 75% in 1940 to just 21% by 1987. Thanks to nationwide reforestation and eco-tourism efforts, he says the nation's forests have since rebounded to roughly 60%. Behind him, rows of chrysalides gleam like polished jade. Gerald lifts one delicately, showing how different caterpillars harden and shift colour. I witness the moment a caterpillar begins to turn green from the centre of its head, hardening into a chrysalis – a silent metamorphosis taking place before my eyes.
The forest transforms at after dark. Sound replaces sight – frogs trill, wings brush against leaves and a faint patter of rain falls through the canopy. Flashlights reveal leaf-cutting ants marching in long lines holding green blades above their heads, strawberry poison dart frogs, a coiled snake and a green basilisk.
As we move farther along the trail, Gerald pauses beside a broad heliconia leaf. "Look from below," he says. I crouch down and peer inside. A family of Honduran white bats cluster beneath the leaf, their white fur shining in the beam. I didn't know that white bats even existed and I'm utterly thrilled.
In the early morning, the low call of monkeys somewhere beyond the trees wakes me. For a moment, I just listen to birds calling, insects buzzing, unseen creatures stirring the leaves. I make my way to the dining area, where white-necked Jacobin hummingbirds sip from feeders. Nearby, dazzling green honeycreepers dart between branches. Shining honeycreepers, their bodies a vivid cobalt blue striped with black, flash through the trees.
Around them, countless other brilliantly coloured birds I've never seen before gather to feast on ripe bananas. I sip a cup of freshly brewed coffee, listening to the layered morning chorus. It's hard to believe this entire world began with a single idea: that planting for butterflies could one day bring back the jungle. A small act that has sparked big consequences – a true butterfly effect.
Costa Rica's rainforest reborn by butterflies
