Local scientists and residents agree – this has been an amazing summer for bioluminescence, a natural phenomenon that creates a bright blue glow in the sea.
Massey Albany marine biologist David Aguirre lives at Hatfields Beach and has seen bioluminescence there, but not with the intense glow of recent sightings around Orewa and Whangaparaoa.
The source of the blue light can be a number of single-celled phytoplankton – mainly Noctiluca scintillans, but also other types.
These species are in the ocean all the time, and seen by boaties and kayakers, but particular conditions bring them close to shore.
David says the blue light is triggered as a defence when the organism is excited or threatened, which is why it glows more when the water is swirled about by wave action or people.
Among the reasons for its prevalence on the Coast are the much-publicised stormwater runoff after heavy rain – the organisms thrive on those nutrients.
Warm temperatures, clear skies and calm seas are ideal for them to reproduce, leading to large groups (blooms), which appear red in daylight.
They drift in the water like rafts, pushed close to shore and concentrated and held within headlands and bays, which is why there have been so many sightings around Whangaparaoa and Orewa.
David says some species also glow in the daytime, but dimly. “Most keep a daily rhythm where they only glow at night,” he says. “An incoming tide and a bit of an onshore wind are ideal conditions for sightings – not enough wind to break up the bloom, but enough to push it in.”
“This summer we’ve had the perfect combination – warmer water, lots of sun, occasional heavy rain and high tide at night.”
Gulf Harbour resident and night photographer Grant Birley first saw the bioluminescence sparkle a year ago in Whangaparaoa and has been chasing it ever since.
He was one of the first to join the Facebook page Bioluminescence Hibiscus Coast, which started last year to help people search for the blue light.
Grant has seen the number of people out looking for it drastically increase recently.
“There were only a handful last summer when I was out, but after a big showing at Manly a couple of weeks ago, it went nuts,” he says.
Towards the end of January, the carpark at Orewa Estuary was completely full in the middle of the night as people searched the shore.
Lisa Bayne Walker of Millwater was looking for it with her family and finally struck gold at Orewa Beach.
Just before midnight, Lisa and her 14-year-old daughter Tamzin saw a flash of blue in the waves and plunged into the sea, fully clothed, to get a closer look.
“We were up to our waists and it lit up our black clothes as though they were covered in stars,” she says. “It was the most magical experience. We stayed in for almost two hours. Definitely one for the bucket list.”
The search is on
Finding bioluminescence is often down to chance. Matthew Davison is looking for a more scientific method, using satellite data. Although he still has much work to do, he says he can now provide advance warning of medium to large concentrations of blooms around Auckland. “I hope to automate the process and scale it up to NZ-wide,” he says. Info: extreme-pursuit.com
Clues for sightings Rain, followed by a warm day, clear skies and high tide at night. Many sightings are a couple of hours either side of high tide. • A slight onshore wind pushes it into shore. • This year it seems more concentrated at Big Manly, Red Beach and Orewa. • Join the Bioluminescence Hibiscus Coast Facebook page.