Irish researchers have developed satellite technology that could help local authorities predict and clean unwanted buildups of smelly seaweed that continue to prompt complaints from beachgoers.
The phenomena known as golden seaweed tides have been a problem in Ireland for about the last 30 years, bringing large deposits that decay, become slimy and give out foul odours similar to sewage.
Dublin residents have long complained of its effects, often confusing the material with sewage discharge.
Scientists from the School of Natural Sciences and Ryan Institute at the University of Galway, who have been studying the patterns and causes of such tides in Dublin over a seven year period, have now made their tracking software freely available to help tackle their spread and effects.
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“It helps you to manage, basically, shores and estuaries and the coverage of organisms that are there,” said Dr Liam Morrison, who led the research alongside Dr Sara Harro.
Their BioIntertidal Mapper software, which analyses images from a European Space Agency satellite, is aimed at assisting scientific and environmental managers to map habitats along the coastline.
Seaweed blooms are an indication of nutrient over-enrichment, which in the case of Dublin Bay has been linked to the waste water treatment plant at Poolbeg.
“The blooms can have a negative impact on the habitat itself and can also have an impact on the recreational use of the beach because you have these large accumulations of seaweed on the shore, and as they decompose they use up oxygen and there is odours associated with them,” said Dr Morrison.
The University of Galway team monitored seaweed coverage at Dollymount Strand in Dublin Bay between 2016 and 2022 in order to build up an understanding of patterns and the specific weather conditions that enable its formation.
That would potentially allow the blooms to be anticipated and prevented, or even simply to help guide early beach cleaning. The researchers noted “numerous” public complaints about the effects of such seaweed in Dublin.
The increase in golden tides, the paper also found, could be attributed to warmer water in the Irish sea associated with climate change. They are most common in the summertime.
In September 2020, Dublin City Council issued an information bulletin following complaints from the public which mistakenly attributed the appearance and odour along the coastline to sewage effluent.
It said material washing up on coastal marshes and beaches during high tides was a naturally occurring seaweed or macro algae called Ectocarpus.
“Toward the end of its lifecycle Ectocarpus quickly progresses through various stages of decay and it is at this time of year the decaying ectocarpus presents itself with characteristics not too dissimilar to foul effluent or sewage,” it said.
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