800 tonnes of sea lettuce was collected from the Matua/Otumoetai foreshore in Tauranga Harbour last week. It’s the first collection for summer, co-ordinated by Bay of Plenty Regional and Tauranga City Councils.
“Sea lettuce is natural but it can be a nuisance to people when it washes up on the beaches. It’s a native algae that flourishes in clear, nutrient-rich water and sea temperatures of around 15-20°C, so Te Awanui (Tauranga Harbour) is a perfect place for it to grow,” said Regional Council Technical Advisor Bruce Gardner.
Mr Gardner said that Regional Council’s scientists have been checking on sea lettuce growth in the lead up to summer.
“It’s normal for sea lettuce accumulations to wash ashore in Tauranga Harbour, especially when contributing wind and tidal conditions align. Despite the build-up at Matua, growth levels throughout the harbour so far are below the long term average for this time of the year and a neutral El Nino/La Nina weather pattern is forecast for this summer. So at this stage we’ve got no reason to expect any exceptionally large blooms this summer,” Mr Gardner said.
Mr Gardner said that the councils will continue to collect nuisance accumulations from popular beaches as needed over summer. He said that the councils have a three-pronged approach to managing sea lettuce.
“We’re reducing nutrient inputs to the harbour by working with land, business and infrastructure owners to clean-up land run-off, we’re funding research projects through the University of Waikato Coastal Science Chair, and we collect nuisance accumulations from busy beaches. No untreated waste discharges have been allowed into the harbour since the 1990s,” he said.
Sea lettuce concerns can be reported to Bay of Plenty Regional Council’s Pollution Hotline on 0800 884 883 or Tauranga City Council on 07 577 7000. Further information about sea lettuce in Tauranga Harbour is available at www.boprc.govt.nz/sealettuce.