Sea lettuce is a naturally occurring green algae native to New Zealand that causes problems for the community when it grows during summer months and is deposited on beach and foreshore areas in large quantities.

For more information about Sea Lettuce in Tauranga Harbour read our Tauranga Harbour Factsheets.

These sea lettuce "blooms" can affect the way the harbour looks, and how people can use the harbour for business and pleasure.  When it decays it produces an offensive sulphur odour.  Sea lettuce can drift around the harbour and nearshore coastal waters and interfere with fishing nets and lines.  It can also affect commercial shipping at the Port of Tauranga, wrapping around ship propellers and blocking cooling water intakes.

The research Bay of Plenty Regional Council has done shows that sea lettuce blooms in Tauranga Harbour are a natural event linked to the El Nino weather pattern.

Sea lettuce abundance at any one location around Tauranga Harbour can change markedly in a rather random fashion due to the effects of winds and tides shifting it about. Despite that variability, the links between harbour wide blooms of high sea lettuce abundance and weather patterns (El Nino - La Nina) as shown in the graph above, is strong enough to use as a tool to make predictions of bloom events. The prediction provided below is based on ENSO models run by the NOAA Climate Prediction Center in the United States.