No sea lettuce has been collected from St Aubin's Bay in Jersey so far in 2026, according to the island's government, which points to a combination of unusually hot weather and changes in farming practices as the likely cause. The seaweed has traditionally built up on the beach each summer, creating unpleasant smells and discouraging people from walking on the sand, but officials say this year's conditions appear to have interrupted its usual life cycle.
Sea lettuce growth in the bay has long been linked to warm, shallow water combined with run-off from nearby fields and treated wastewater. The Environment Department said the algae typically reproduces in May, and this year's early and prolonged heat appears to have thrown that process off course.
Why has sea lettuce growth stopped this year?
According to the department, the timing of the heat coincided directly with the plant's key reproductive window. A spokesperson said:
Sea lettuce mainly reproduces in May. The unusually high temperatures we experienced during that period were likely to have disrupted its normal growth and reproduction.
Jersey recorded its hottest ever May day this year, with temperatures climbing to 29.2C (84.5F), and the heat continued through the summer months rather than easing off as it might in a typical year.
How does the heat connect to other water issues this year?
The unusually warm and dry spell that disrupted sea lettuce growth was also felt elsewhere in the island's water system earlier in the summer. According to an earlier report on Jersey's water demand, Jersey Water recorded its highest demand since the 2022 drought during a June heatwave, prompting calls for residents to conserve water even though reservoirs remained at 89% capacity at the time. The two developments suggest the same stretch of hot, dry weather has had a broader effect on the island's water and coastal conditions this year.
What role have farming and treatment changes played?
Alongside the weather, the government credited ongoing efforts to cut nitrate use in agriculture with helping to reduce the nutrient build-up that normally feeds sea lettuce growth. Officials said the work of the Action for Cleaner Water group, a partnership between Jersey Water, the government and representatives of the island's farming and dairy industries, would support further reductions in future. The government has previously stated that nutrients washing in from outside the bay, run-off from streams carrying fertiliser, and treated wastewater from treatment works all normally contribute to the algae's growth, a point reinforced in the department's published sea lettuce guidance. Separately, a 2023 report on the island's infrastructure said engineers were hoping that improvements to Jersey's sewage treatment works would help cut the volume of green seaweed accumulating in the bay, according to an earlier broadcaster's report. A separate account of the island's new £75m Bellozanne wastewater treatment plant said it was expected to reduce nitrate run-off feeding into the bay, according to a local news outlet's coverage.
How has sea lettuce affected the coast in previous years?
In recent summers the algae has been removed in large quantities and put to use on the island's farmland. Almost 3,000 square metres (32,300 sq ft) of sea lettuce was taken from the beach in 2025 for this purpose, and a separate account of the 2024 season reported that more than 3,000 tonnes had been removed from the bay by late July that year, with all of it spread on island fields, according to a local newspaper's report. The government's own guidance notes that infrastructure teams typically use a Surf-Rake to clear light amounts of the algae during quieter periods, usually early in the morning when tides allow, and that sea lettuce has long been moved down to the low tide mark so it can be carried away by the tidal flow.
What does this mean for Victoria Marine Lake?
Sea lettuce build-up has previously complicated maintenance work elsewhere on the coastline. A £315,000 repair effort at Victoria Marine Lake was reportedly hampered by the algae, with plans for more extensive repairs pencilled in for spring 2026, subject to funding, according to a broadcaster's report on the lake's repairs. A States Assembly document said work would continue through 2026 to make the lake as safe as possible while officials work to confirm the full costs of repair and ongoing annual maintenance, according to the States Assembly document.
What happens next?
No specific date has been set for a further government decision on sea lettuce management beyond the continuation of the Victoria Marine Lake repair work and ongoing monitoring of nitrate levels in 2026. Officials appear to be treating this year's absence of sea lettuce as a result of favourable, if unusual, conditions rather than a permanent shift, with the Action for Cleaner Water initiative expected to continue its longer-term efforts regardless of this summer's outcome.
Key Facts
- No sea lettuce has been collected from St Aubin's Bay in Jersey so far in 2026.
- Jersey recorded its hottest ever May day this year, at 29.2C (84.5F).
- Almost 3,000 square metres of sea lettuce was removed from the beach in 2025 for use on island fields.
- A separate report found more than 3,000 tonnes had been removed by late July 2024.
- A £315,000 repair effort at Victoria Marine Lake was reportedly hampered by sea lettuce, with further repairs planned for spring 2026.
