Nicky Haigh

Nicky Haigh

Ochre-hued slick caused by algal bloom

Bloom of Noctiluca scintillans stains surface of Ladysmith Harbour and surroundings flourescent orange over the August long weekend.

The mysterious source of a massive ochre-hued slick spanning much of Ladysmith Harbour and sections of Stuart Channel Friday, Aug. 2, has been solved.

Multiple inquiries with various regulatory agencies regarding the potential source of a spill resembling “hundreds of gallons of copper paint” led us to Nicky Haigh, an expert on harmful algal blooms, or HABs, at Vancouver Island University in Nanaimo.

Haigh, who works with VIU’s Harmful Algae Monitoring Program (HAMP), said the bloom carpeting Ladysmith Harbour “was almost certainly Noctiluca scintillans,” adding that she saw similar blooms of Noctiluca the weekend of Aug. 3-4 around northern Salt Spring Island and offshore from Crofton.

Noctiluca scintillans is a species of dinoflagellate — a single-celled protist — with large, spherical cells that range up to two millimetres in diameter, big enough to be seen with the naked eye. They emit light when disturbed — bioluminescence — and under certain conditions form greasy, fluorescent-orange blooms that coat the surface of the water.

“It’s the only bloom I can identify without having to use the microscope,” Haigh wrote, referring to a Noctiluca bloom at Ladysmith Harbour she photographed in late June.

Diana Varela, a professor of marine biology at the University of Victoria, confirmed that Noctiluca blooms do not result in the production of toxins. As such, labelling them as “red tides” is both misleading and inaccurate, and Varela prefers the term HABs.

As to the extent of the bloom, Bud Bell at Sealegs Kayaking said he paddled through a “copper-red slick” that “stretched for miles” along the surface of the water off of Coffin Point, adding that his guides reported similar sightings all the way from the northern tip of Ladysmith Harbour to Chemainus.

Gabe Nicholson, a passenger on WestJet Flight 3109, said he saw boats slicing through bright orange slicks that spanned entire channels between islands during his final approach to the Nanaimo Airport Sunday, Aug. 4.

Haigh said Noctiluca blooms are triggered by “the presence of a good food source — generally a diatom bloom.”

Noctiluca are classified as phytoplankton, Haigh added, but unlike most phytoplankton, they feed on diatoms and other plankton for energy rather than producing their own via photosynthesis, meaning they “act like zooplankton.”

According to Haigh, Noctiluca blooms are “quite common,” and in the event of a future bloom, Haigh said HAMP lab staff would “be happy to field calls from the public” the next time they see “exciting things” out on Ladysmith Harbour.

Haigh can by reached at 250-740-6354 or Nicky.Haigh@viu.ca.