A Galway Hooker is moored in the small Co Wexford harbour of Cahore Point, and a group is being addressed by a deeply tanned woman in a strong blue T-shirt. The subject is waste management and here, as throughout much of Ireland, the problem is obvious: local residents are concerned about the litter strewn about their environment.

The speaker is Karin Dubsky, environmentalist and co-ordinator of Coastwatch Ireland. Her approach is always based on science and logic - "The impact of waste on the environment: how does it happen and how to avoid it." Alongside the common sight of plastic bags and bottles is marine waste: discarded fishing ropes, nets, angling lines and newspapers. All present a threat to protected animals such as dolphins and turtles, as well as fouling boat engines. A local woman also raises the subject of discarded nappies - now a common feature of Irish beaches.

Then there is the tradition of dumping old fridges and sofas. Dubsky is energetic, hyperactive and motivated by a crusading belief in solving problems. She sounds positive. Her concerned optimism has always countered her exasperation. But she is practical as she tells her audience "you put a lot of effort into something such as campaigning for information about water quality sample results to be made available at beaches. We achieved that in 1992. This service is paid for by the tax-payer, so you think `wow what an achievement'. Then there is the frustration of it not being implemented." She has also learnt a great deal from experience. Even if a beach looks clean, "always look behind the walls; there you will find rubbish, often a metre and half of it".

Even when arguing points on a particular issue, she remains a scientist, always alert to the evidence before her. But being a watchdog has not blinded her to the joys of the natural world.

Cahore Point is a clean harbour, with a particularly rich eco-system. Before the practical talk began, she had her audience standing on the harbour wall, marvelling at the generous supply of kelp, eel grass and variety of sea weed, "all proof that this is a clean harbour". Even so, no place is safe.

As if on cue, enter the double Jetskis. Banned by law in some areas, they head for places where they are still free to invade, crashing through the water like maverick bikers on water skis, presenting a threat to swimmers as well as causing oil and noise pollution.

Later, driving back from the beach, as stray plastic bags waft across the road, festooned on trees and hedges, she stops her car to draw attention to the rampaging development of suburban housing estates masquerading as holiday homes which are beginning to dominate the Co Wexford landscape. She doesn't have to point them out; they are impossible to miss.

Now 46, and long famous in Ireland through founding the Irish Coastal Environment group concerned for the future of Dublin Bay when it was polluted by raw sewage, she dashes about, describing, explaining. Clean Seas is a joint Ireland-Wales (partly EU-funded) initiative run by Coastwatch Ireland and the Keep Wales Tidy Campaign. It aims to reduce ship/harbour-generated waste in line with Marpol, the International Convention for the Prevention of Marine Pollution from Ships and an impending EU directive. Dubsky's project consists of visiting about 30 harbours along the south-east coast from Meath to Waterford, where she discusses, listens and advises on waste problems and how to solve them. There is a crisis, though: Clean Seas has lost its commercial sponsor, Esat Digifone, because it was taken over, and the Coastwatch Clean Seas project urgently needs a replacement.

She has also recently been through five court cases, including a hearing in the Supreme Court, battling to protect an important bird-feeding ground on a threatened wetland area in the Boyne estuary which is a designated Special Protected Area for wild birds. Dubsky took on Drogheda Port Company (DPC) because its dredging operations, involving the dumping of 700,000 tonnes of dredge spoil, was damaging the wetlands area. Of huge concern was the plan to create new mud flats by spraying herbicide on the Spartina grass which the DPC, with the support of Duchas, deemed expendable but which provides a valuable habitat.

The battle has been exhausting. Dubsky, with her thin girl's body and wayward fair hair, remains girlish, if worn out. Years of little sleep have finally caught up on her. She holds a container of herbicide in her hand and points to the label. "Look. It even says it is dangerous to aquatic life. What more proof do they need?" A few hours later all her work is justified. The Minister for Arts, Heritage, Gaeltacht and the Islands, Sile de Valera, refused permission to spray the wetland. "While I'm absolutely relieved, the battle is not over - either an alternative feeding ground for displaced birds has to be provided, or the dredge spoil has to be moved."

As for the new levy to be placed on plastic bags: "I'm hoping that it will be introduced in time to see a significant reduction in the number of plastic bags we find on the shore in our autumn Coastwatch survey. I am delighted that the levy money is to be directed back into environmental projects. Ideally it should go into waste management and particularly the minimisation and reuse of packaging such as cloth bags." Just as the Government dispatched a millennium candle to every household in the State, surely the same process could be applied to providing each home with two canvas shopping bags?

Products, says Dubsky, "are seriously over-packaged". She is also concerned about what she describes as "please do not recycle me" packaging in which several non-compatible materials which cannot be recycled economically are mixed together. Packages such as "a milk carton with a plastic top or a yoghurt pot with a foil top, or juice in a plastic aluminium and paper pack which looks like paper . . . this sandwich of material is impossible to recycle economically."

Her concern for the environment developed early. "When I was at Trinity a group of us said we would boycott our practicals if they didn't stop experiments on live frogs." Even before that though, as a schoolgirl, she objected to a youth fishing outing because the fish were thrown on to the deck, judged for a competition, left to die but were not later eaten. "I objected to them being fished for fun."

She is not self-righteous; she is merely living by the code she learnt from her parents. Dubsky describes herself as "a north European mongrel". Her parents were caring people who did things; she has inherited an ability to act as well as think. She is energetic and impulsive, but she also deliberates. Still, as she roots about in a small pond in her tangled woodland garden, yards from the beach, searching for the frog which just slipped out of sight, she does not come across as a typical scientist and mother of four.

Born Karin Falkenthal in Bonn in 1954, she grew up mainly in Germany, "but in several parts; we moved around a lot". Her mother grew up in Riga, in Latvia, "amongst other places throughout the Baltic States", eventually settling in Riga. "My mother had lost her first husband as a result of the war and already had three daughters and a son by the time she met my father." Dubsky's father, Gert Falkenthal, who served in the last German Calvary regiment, came from a place just north of Poznan, at that time in West Prussia, now part of Poland. He had grown up on a large estate and stud farm, and always loved horses. On his father's retirement, he took over the stud but then war broke out and his life changed.

Karin Dubsky has vivid memories of her early life in Germany and remembers walking to school through a forest. "We were given very good advice. If we ever saw a fox with rabies, we were told to, `quick, climb a tree'." She enjoyed this and was soon exploiting it as a way of spending more time in the woods. "It was a great excuse if you were late for school." But her parents would eventually realise they could not make a living from their land in Germany.

"The German government had a policy of encouraging refugees from the East to emigrate and would give a financial contribution assessed according to the value of the land."

Her parents considered three destinations: France, Canada or Ireland. They chose Ireland. "My older brothers and sister were starting college, my parents did not want to go as far as Canada, and it had filtered back that Ireland was a country with a love of horses, and that appealed to my father. My mother had been a teacher but she lost her job because she refused to join the Hitler movement." Dubsky points out the irony of her mother having finally received unsought compensation "out of the blue" quite recently, for the loss of that teaching job more than 50 years ago.

The Falkenthals came to Ireland and purchased St Kieran's House, an "out" farm, in Saltmills, Co Wexford. "It was one which had had the roof removed in order to be exempt from rates." The couple stayed on and worked it with "enormous help from the local people" while their six children, including Karin, were farmed out with relatives or were at college in Germany.

"I spent that final year in Germany living with my paternal grandmother and my aunt. They were very good to me but I hated living in the city, and missed climbing trees." On her 10th birthday, March 18th 1964, she arrived in Ireland and, with the exception of five years spent in the Czech Republic in the 1990s, is settled here.

Her accent remains strong, and Dubsky speaks German at home in Ballymoney, Co Wexford. "My father never really learnt English," she laughs. "Well, he spoke a strange version of Wexford English but it was mainly Polish and German." She describes him as a big, kind man with huge hands, a person who looked around him and saw things. As a child at school in Ireland she was often teased for being an outsider and there have been times as a campaigner when she has been dismissed as "an interfering foreigner". She finally found roots and remembers the day she realised Ireland had become home.

"We were out on a walk and my father picked up some soil and he felt it, and he said, `this is going to be our new family home. I am going to be buried here'." Suddenly, after two generations of travelling about Europe and always seeming to collect more relatives along the way, the family had a home.

Asked what she was like as a girl she offers a thumbnail sketch of "a misfit" interested in many things. "At times I did very well at school, at others, not so good. I always loved art so when I was doing badly at everything else, I could always say to myself: `At least I can draw'." Her time at Newtown School in Co Waterford helped make her a natural scientist. On completing the Leaving Cert with eight honours, she was too young for university and travelled for a year, working at a number of jobs including sheep farming, before returning to Ireland where she entered the natural sciences faculty at Trinity College. She married Paul Dubksy, himself of mixed Irish/Austrian background, as a student. Her first baby was due just before her finals. Her domestic situation and the arrival of a son interrupted her study for a year. But she returned and completed her degree specialising in quantitative zoology. Two more sons were born before she completed a masters in environmental sciences with a thesis on mussel population dynamics.

The interest in coastal areas is easy to explain. Wexford was her introduction to the sea. Her career as an environmental campaigner has been shaped by her specialist knowledge. Dubsky is probably better known in Europe than she is here. In 1988 she ran a Coastwatch Europe survey on a trial basis in test areas in five European countries. Later that same year she was a co-founder of the Irish Clean Air Group and produced a strategy for improving Dublin air quality. Access to information is central to her approach to environmental issues and Dubsky has always maintained that only by getting people involved in surveys and other schemes, will they develop an interest in such issues. "Public information is so important."

Having run the Blue Flag award scheme between 1987 and 1993, she stresses the need for a balance between encouraging people to visit areas with the need to protect such habitats. In 1991 she ran Ireland's first international conference on waste management. On the subject of incinerators, she says: "Our record with accidents is not good. Unless an incinerator could be placed within one mile upwind of the Dail or Temple Bar, I would fear for the management of it."

During her five-year stay in the Czech Republic she was active in opening the East European office for Coastwatch Europe. Throughout that time she travelled between the Coastwatch head office in Trinity College and Prague. Her mother still lives on the family farm. Helga Falkenthal returned to Germany for a few years in the mid 1990s, "but she had to come back, she was homesick for Wexford".

Ten years after the birth of her third son, Dubsky had a daughter. All the while she has continued working. There have been successes; there have also been failures. "I have felt frustrated," she says and recalls noticing bulldozers moving in on a site one Friday afternoon. "I was on my way abroad and had no time. I stopped and phoned the relevant county council office and was informed no complaints could be taken over the phone. I would have to write in. They refused to listen." She shrugs at the memory. "I think policies are no good until they are implemented. But. . ."

Time is always a problem. Phone calls bring her on journeys across the country trying to help - and she does. Toasting with Austrian wine what could be the demise of the plastic bag, Dubsky, the unrelenting activist, looks happy. Tenacious but pleasant, she could hardly be described as a cranky eccentric.

Are we Irish a dirty people? "We are careless," is how she puts it.

For more information on Coastwatch, phone Karin Dubsky on 055-25843 or email Dubsky@iol.ie