Green peril returns to Bay

SEA OF GREEN: Sea lettuce is abundant around the Bay at the moment. Here it is seen in the waterway between Chapel St and Maxwells Rd in Pillans Point. PHOTO/RUTH KEBER

It's green, slimy and it stinks - sea lettuce is back in the Bay.

Bay of Plenty Regional Council has received five complaints and inquiries this summer that relate to five different parts of the harbour from Ongare Point at the northern end to Tauranga City harbour and ocean beaches.

Bruce Gardner, Tauranga Harbour Principal Advisor, said the green algae finds its way back to the beach year on year because of the clear, shallow and temperate waters of the Tauranga Harbour, Maketu Estuary and Waihi Estuary, which all provide an ideal habitat for it.

"Normally, there are low amounts of nutrients in our harbour and estuaries, but any increase in nutrients will increase growth rates."

Mr Gardner said nutrient levels can increase naturally, or as a result of land runoff or discharges.

Bay of Plenty Regional Council worked in conjunction with Tauranga City Council to engage a contractor who has specialised equipment for clean-ups, he said.

"We will clear nuisance sea lettuce accumulations from high public use areas.

"Already this summer we have completed two clean-ups at city beaches, Fergusson Park and Kulim Park."

The blooms of sea lettuce have been checked every two months since 1991 by Bay of Plenty Regional Council.

Mr Gardner said the sea lettuce blooms in Tauranga Harbour are controlled by natural events and would be less clearly linked to nutrient runoff from land but research was being done to help councils understand more about nutrients' input into the harbour and how to better manage it.

"The research being funded by Bay of Plenty Regional Council is to better understand the inter-relationships between the various factors that drive the blooming of sea lettuce. Research is also being done to find out more about the effects of sea lettuce on marine life that it smothers when it accumulates on intertidal areas."

Mr Gardner said there were no public health warnings "but sea lettuce can be used as a garden or orchard mulch, sparingly to avoid high levels of salt building up, which would kill sensitive plants.

"It can also be used to make compost, but needs to be thoroughly mixed with other compostable materials."