Macroalgae (seaweeds) are the subject of increasing interest for their potential as a source of valuable, sustainable biomass in the food, feed, chemical and pharmaceutical industries. However when you are out for a swim, the unpleasant smell and mat of brown slime (mostly brown) is not interesting but rather a turn-off.
In May 2010 an Irish Times article reported :
FOUL SMELLS and the appearance of brown sludge on beaches around Dublin Bay are the result of sunny weather and not sewage, Dublin local authorities have said.
The “brown sludge” as it is termed, is a seaweed called Ectocarpus. This seaweed likes to grow with the correct light conditions – such as we have been experiencing over the past month and also high nutrient content. There are key sources of these nutrients that are leading to the proliferation of the algae. However, with some of the sources of nutrients being shut down over the COVID-19 crisis, it seems that inputs from runoff and sewage might be the main culprits.
There are many brave people swimming today in Dublin Bay and there is quite a bit of brown seaweed present. It would be great if we could see a speedy improvement in the wastewater treatment plant – we know that plans are underway – because this could improve our water quality in the bay for everyone all year round.