Rogerstown Estuary: what’s the big deal?

Rogerstown Estuary: what’s the big deal?

by Tom McCloughlin, DCU Water Institute.

For those of us living in east Fingal, there is an issue with transport. We live near the coast, but to travel north or south we have to go around the estuaries of Rogerstown-Turvey (and Broadmeadow, and Baldoyle) and they, because they are protected areas for wildlife, appear to be black holes in our local geography. We go around them but never to them. When you do they can appear empty and devoid of any life. At high tide, they have a uniform skin of water, and at low tide fine deep mud and deeper channels of the various streams entering them. However they are the power-houses of life here and elsewhere.If you are a fisherman you may wonder where your catch comes from, where do the fish reproduce and if you are a birdwatcher, you might wonder what do all the birds eat? The estuaries are where many fish species caught at sea come here to reproduce because the estuaries are sheltered but also because they provide food for the young, just enough to keep them going until they get out to sea. The estuaries are where birds from Canada and the Arctic in general come in our winter to breed and feed - where it is too cold, and where birds from Africa come in their summer to do likewise - when it is too warm. It’s hard to think of Rogerstown as this great ‘transport hub’ of life. The birds come to feed on a variety of animals living in the mud, and each species has its preference (but like us, they’ll try different flavours!). The picture shows the ‘favourite’ food for each bird.The little mud animals depend on clean water entering the estuary, so if pollution enters a stream at Ballough, it has an effect at Rogerstown. Too much phosphate and the water is starved of oxygen because certain algae go mad. The mud animals die, and the birds arrive to find less food than before. Breeding fails, the birds move on to other already cramped areas, and the breeding cycle is interrupted reducing the population of birds who keep the fish and mud animals in check. Without them, the mud animals in turn over populate for the available nutrients and space, and they in turn crash. But all is not lost. If we keep our litter, rubbish, pollution, and dumping to ourselves, the estuaries will thrive and become the glory of Fingal, as great international hubs of life and biodiversity and a source of pride to show the rest of the country how to work for the environment. Rogerstown estuary has suffered a lot due to humans. The railway (1843) split the estuary in two, making the inner estuary become salt marsh higher up (instead of mudflat) and reducing the flow of water around the inner estuary. The landfill (1984-2012) reduced the area of the inner estuary, buried a stream, and remains a stockpile of unknown levels of pollution. Fortunately, no elevated levels of radiation nor dissolved pollution appear to be leaching into the surrounding areas to date, but we have to keep monitoring the situation, and we are. Fly-tipping particularly on the medieval tidal road joining Ballealy Lane to the Channel Road releases physically dangerous substances (sharp metal, broken glass, wire, plastic cord, etc.) to wildlife and humans alike. Occasionally cars were burnt out there too releasing toxic fuel, oil and lubricant liquids into the mud - it’s never all burned away. And water entering the estuary at times has high levels of phosphate from domestic outflows. But all is not lost nor beyond repair. Fingal CC has turned the landfill into a park, and students and staff from DCU have assisted in ongoing beach cleaning, and a number of individuals have tried to encourage ethical walking (without disturbing wildlife) around the estuary. So rather than places of exclusion, estuaries can become places where humans and wildlife can live in harmony as good neighbours once we understand their needs.

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