[USA] If you want to night surf in glowing blue waves or dance on sand that “lights up” with bioluminescence on Virginia Beach, Va., you might want to hurry.
Friday night surfers and hundreds of beach goers flocked to the Sandbridge section of Virginia Beach to revel in what experts say is likely the result of a healthy algae bloom.
Wildlife biologist Forrest Galante says that “Generally it’s completely without hazard to you as a swimmer or surfer. How long it will last is all over the map because bear in mind, you’re talking about living organisms.”
“These living organisms are living in the currents and tides of the ocean,” Mr. Galante adds, “So if you get a strong wind event or a large current event they can be gone in a couple of minutes. But if you don’t get one of those events and there’s a ton of these things it can stick around weeks.”
“I used to time certain surf trips so that I was surfing in bioluminescence at night,” Galante says.
Alison Phillips who works at Surf and Adventure on Sandbridge Beach, was among those who experienced the awe of an oceanfront Friday night that looked more like something out of the movie Avatar than a typical night surfing.
“It was totally rad,” MS. Phillips says in an interview. “We didn’t surf or disturb the water because we didn’t know what was causing it and if we might hurt it. But it was amazing. I’ve lived here all my life, 22 years and I’ve never, ever seen anything like this before.”
Galante explains that swimming and surfing in this bio bloom won’t harm the creatures causing it.
“It’s a chemical reaction that’s released by oxygen,” he explains. “The organisms emit a light-emitting pigment. Basically that reacts with oxygen. So when you react with the waves and bring excess oxygen into the water you glow. When the waves break and oxygen is getting mixed in the water is dark but the wave breaks, the foam, is emitting the light.”
Is this a sign of a healthy ocean?
According to Galante, bioluminescence occurs widely in marine vertebrates and invertebrates, including some bioluminescent bacteria. This kind of phenomenon, he says, can be caused by an upwelling of cold, nutrient-rich waters from the ocean floor, or by stagnant water in bays, or by water pollution.
“It can go either way as to being healthy or unhealthy,” Galante says. “If there’s an algal bloom that’s happening because of a major upwelling event where deep water currents are coming up to the surface in the ocean that’s great. That means it’s healthy and lots of good things are coming to the surface.”
Conversely, “If it’s in a bay where the waters are really stagnant, like when you leave a pot of water out in the sun too long and there are no nutrients you get one kind of dominant algae (like a red tide) and that algae is light emitting, it can be a sign of a negative effect.”
Since no red tides have been reported in the area, Galante says this is likely an outbreak of dinoflagellates, perhaps, Pyrodinium bahamense, a plankton that’s known to generate bioluminescence when agitated. These single-celled creatures measure about 1/500th of an inch and release tiny bursts of light that shine hundreds of times bigger than themselves.
Michelle Coley, at the Virginia Aquarium and Marine Science Center, agrees: “This is bioluminescence created by creatures called dinoflagellates that will present this sort of phenomenon during the late summer and early fall when water temperatures are warm and the sea is calm. This ‘light show’ happens due to their increased numbers.”
According to the Smithsonian website, each dinoflagellate bursts into light when it feels pressure against its cell wall. The light is given off in an instantaneous process; when you add the light bursts of 750,000 dinoflagellates per cubic foot of water together the effect is spectacular!
Galante explains that, “Almost all marine bioluminescence is (greenish) blue in color because the blue-green light [wavelength around 470 nanometers] transmits furthest in water. Most organisms are sensitive only to blue light, although the luminescence in this case is readily visible to the dark-adapted human eye.”
Also, he adds that the intensity of luminescence of these photosynthetic creatures depends on the intensity of sunlight the previous day. The brighter the sunlight the brighter the waters will glow that night.
Galante concludes, “It makes it a really fun time to be in the water.”
View original article at: Virginia Beach bioluminescence: What’s lighting up the water?