WE have found remote, west Cork beaches free of the noxious green sea ‘lettuce’ that has plagued so many Irish estuaries and strands.
Small coves fare better.
This weed is an abomination. Washed ashore by successive tides, it builds into metre-high ridges running the length of our best beaches, where it dries and forms a film-like skin on the surface. The weed underneath, heated by the sun, becomes a putrefying aerobic digester, blocking access to the sea.
The sand-banks and mud-flats which, ten years ago, were scoured by the tides are now, from May to October, covered in mats of weed, some still green while others become thick, white carpets that are lifted to float the incoming sea.
The proliferation of sea ‘lettuce’ is international. The cause is ascribed to nitrates from farms reaching the sea where, as sure as they boost grass crops on land, they grow crops of marine ‘lettuce’ in the ocean.
Sea ‘lettuce,’ ulva, is benevolent in nature; its proliferation, due to human activity, makes it toxic. The filmy, green fronds are attractive, and full of vitamins and trace elements. In Israel, it is grown in a controlled environment, then dried and sold as nutritious, mineral-rich human food. Some scientists propose that if grown in vast but controlled quantities (far from land, one would hope), sea ‘lettuce’ would reduce oceanic acidification, which now seriously threatens corals, shellfish and other life essential to the marine food chain.
Sea hares, pretty sea slugs often found in rock pools, graze on it, as do manatees and dugongs, large walrus-like sea cows of warm rivers and oceans. However, manatees could not survive in our cool-temperate waters and one would require legions of sea hares to make any appreciable incursions on the millions of acres of sea ‘lettuce’ around our coasts.
So, what is to be done? If the weed is left to grow, it will assuredly do so, proliferating exponentially. If the coast of Ireland, world-renowned for its beauty, is not to be colonised by it for all time, and the visitor-revenue our coasts attracts lost forever, something must be done to curtail this plague.
Local councils, the Department of the Environment and the Environmental Protection Agency must realise that the situation is now critical, and prioritise a pan-global search for methods of environmentally-safe eradication or control. The cost of a solution will be cheap in comparison with the loss of tourism revenue if measures are not taken, and the longer a radical approach is delayed, the greater will be the cost.
Marine biologists in the US have demonstrated that removal twice per season depletes the weed’s ability to re-colonise. In an overall plan of harvest-and-process, collection costs could be defrayed and the crop could even turn a profit, delivering a bonanza in cheap organic crop fertiliser, or providing significant amounts of ‘free’ fuel from biodigesters producing gas and power.
In shallow estuaries — where it thrives and from whence it is washed onto resort beaches — the weed floats in thick, cohesive, slow-moving rafts on the incoming and outgoing tides. These rafts could easily be apprehended and dragged aboard large, shallow-draft, flat-bottomed boats, with sterns that lower like those of landing-craft of World War II.
Sliding the weed-raft from the sea surface and up the boat’s ramp could be achieved with a custom-made, lightweight rake or a conventional agricultural harrow powered by the simple winch used by lobstermen to haul pots. When filled to safe capacity, the barge would head for shore, where the contents would be JCB’d into an articulated truck for disposal by burying in quarries, mulching down in pits for fertiliser or depositing in biodigesters.
Using JCBs to daily scrape the weed from the tide line of the resort beach and dumping it at one end (for a high tide to wash it back in) wastes money and doesn’t work. Year by year, coastal dwellers see the onward march of green; it is an indisputable fact. It has never reduced, summer to summer, but always increased.
If the implementation of a solution were to cost millions, we could understand the delay. But that is not so. It is simply that government has not taken cognisance of the awful scenario and its consequences. We voted this new government into office. We must insist that its ministers immediately formulate a programme to save our coastal heritage.
a d v e r t i s e m e n t
This appeared in the printed version of the Irish Examiner Monday, July 18, 2011
