What causes those electric-blue flashes at the local boat ramp?

Tiny single-celled organisms are responsible for spectacular marine lightshows Don't panic if you see an electric-blue flash next time you're dipping your toes at the local swimming spot, it's just bioluminescence. Videos showing the phenomenon, which appears as a blue glow in the water when it's disturbed, were posted over the weekend, taken at boat ramps around Brisbane. Queensland doesn't see bioluminescence as much as New South Wales, or Tasmania in recent years, but when conditions are right it can be spectacular. Loading...Bioluminescence refers to a glow released by chemical reactions taking place within a tiny marine species of dinoflagellates, Noctiluca scintillans. These minute unicellular creatures — also known as sea sparkles — feed on diatoms, algae even more microscopic than they are, and use photosynthesis. 'A little bit unusual' Griffith University Australian Rivers Institute Professor Michele Burford said while bioluminescence is a trait of many marine species, the blooms seen in Brisbane were caused by species of dinoflagellates. "They produce this bioluminescence in response to some sort of threat or movement of water that causes them to do this chemical stimulation of a light pulse," she said. "They're tiny little things, but because they can gather together in blooms or form concentrations near the water's edge, that's when you see that luminescence, which looks like one thing but is actually a whole lot of tiny little organisms all lighting up at the same time." The dinoflagellates, like most plants, absorb nutrients from their environment and photosynthesise energy from sunlight, but Professor Burford said it was slightly more complicated. "The thing about dinoflagellates, they're a little bit unusual. They're kind of halfway between an animal and a plant in the way that they work in the natural environment,"she said. Bioluminescence is not uncommon in the natural world, according to marine ecology expert and senior lecturer at Griffith University, Vincent Raoult. "They go from really small organisms like the phytoplankton to slightly larger ones like little marine zooplankton, like copepods which are a tiny crustacean, all the way up to very large organisms such as squid, and even some shark species bioluminesce." Dr Raoult said it wasn't clear yet why the organisms flash their lights, and there were a lot of potential explanations. "One of them is communication, and that can be communication with other organisms … in the form of a warning, or it can be in the form of telling other organisms to be aware that they're there," he said. He said it was also common as an attractant among animals living in the dark depths. "In really deep sea environments … it's in fact one of the only sources of light, and as a result it's used both as a warning cue and also as an attractant to lure food." Glow hunters For those on the hunt for bioluminescence, there are some steps you can take to maximise your chances. While it's present in the daytime as well, it's much more obvious at night. Try to pick a particularly dark night, as a bright moon can really take the edge off that neon-blue glow, and get to the location a couple of hours after sunset. "In Brisbane at least, we tend to see it in the winter months," Professor Burford said. There are some known hotspots in south-east Queensland with potential for the phenomenon. Professor Burford said the lower Brisbane River especially can have blooms in the winter months, "so it isn't a bad place to go on a calm winter's night". "But to a degree, there's an element of luck. Sometimes you get lucky and sometimes you don't,"she said. Bioluminescence is generally not an indicator of an unhealthy waterway, Professor Burford said, and Dr Raoult agreed. "In general, it's perfectly safe. I would just be wary of warnings that might have been put out by councils and so on for water quality more generally," Dr Raoult said. "But I would certainly not link a nice bioluminescing ocean with an unhealthy habitat that might be dangerous." Professor Burford said citizen science was a "great vehicle" for learning more about bioluminescence. "Certainly people posting where they're seeing it and when is a valuable resource because you can't be out monitoring everything all the time and typically people don't monitor at night when they're looking at water quality. "So, it's good to have that information from the public."