The sea lettuce forecast

Finding out if there's going to be a massive sea lettuce problem this summer is difficult, according to Bay of Plenty Regional Council's Tauranga harbour principle advisor Bruce Gardner.

The perception of how bad sea lettuce, is depends a lot on the weather, says Bruce.

When asked if there were going to be knee-deep drifts of sea lettuce on the Mount Main Beach this summer, Bruce says 'it all depends”.

Last year there was a huge dump of sea lettuce on the Mount Main Beach, but not much in the harbour.

'Giving you a prediction is going to be really someone sticking their neck out, I think,” says Bruce.

'The sea lettuce situation in the harbour at the moment, especially in the southern part of the harbour from Omokoroa down to the city, is still at relatively low levels compared with bad seasons.

'But that could all change. Things can change really quickly and the climate predictions are that we are heading towards an El Nino summer.”

Bruce says indicators include the prolonged period of westerly winds that we've had, and cooler ocean water temperatures, which usually result in quite a lot of sea lettuce in the harbour.

But other factors come into play behind large accumulations of sea lettuce at the main beach.

'Last summer, for example, when it was not a particularly bad year for sea lettuce we still got quite a lot of it coming up on the beach at the Mount,” says Bruce.

'So there are some different factors in play. Wind direction and strength, and current and tide all play a part.

'So even though you may have a huge amount of sea lettuce in the harbour, it doesn't necessarily mean it's all going to end up on the Mount beach.

'It can at times just go straight out and you never see it. You usually see some on the Mount beach, but not huge amounts

'And then in low years, like last year, we got quite a lot on the beach simply because we got quite a lot of onshore winds; it was exiting out the mouth of the harbour with currents bringing it back around to the big dump on the beach.

'Then two days later a nice full high tide and an offshore wind – and it all disappears. So it's really, really difficult to predict or to say what the situation will be, especially with the Mount main beach.

Bruce says it's a bit more easy to predict what might be happening on the inner harbour beaches 'but on the main beach it can still be a bad year and we not get much, or it can be a very light year and we get a lot out there”.

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1 comment

A Green Wave

Posted on 28-12-2014 07:58 | By Disappointed

10 days ago the Mount Main Beach was full of sea lettuce. There wasn't a large accumulation on the beach itself but it was so thick in the water the foam of breaking waves was turned green. Looking at the large amount of lettuce already in the harbour (low tide in Rangataua Bay is most disturbing) this summer does not bode well for beach goers or any resident living within smell of the inner harbour shoreline.


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