I'm not even going to attempt to explain this as well as Phil Hart did here on his blog. However, this phenomena is too awe inspiring not to share. If you find this interesting, definitely click on the hyper link to get the whole story behind what exactly is going on here.
The Gippsland Lakes are a network of lakes, marshes and lagoons in east Gippsland, Victoria, Australia covering an area of about 600 km sq. The lakes were formed by two principal processes. The first is river delta alluvial deposition of sediment brought in by the rivers which flow into the lakes. The second process is the action of sea current in Bass Strait which created the Ninety Mile Beach and cut off the river deltas from the sea.
Long story short (again, check the hyperlink in the first paragraph for this amazing story), in the summer of 08/09, there were a series of fires, a low pressure system dumping over 100 mm of rain, and a 1 in a 100 year flood that resulted in ash and soil, rich in nitrogen and other nutrients, washing into the Gippsland Lakes. The rain and flood water also increased the leve of saline in the Lakes as the higher water level facilitated greater mixing with seawater at Lakes Entrance. This lead to concerns over an outbreak of blue-green algae.
Directly from Phil's blog:
Early analysis identified the cause of the green tinge as an algal outbreak of Synechococcus...In contrast to the widespread bright green of the Synechococcus, Noctiluca Scintillans was visible during the day as localised murky red patches, often building up on sections of shoreline facing the wind during the day. At night though, Noctiluca Scintillans produced a remarkable form of bioluminescence (popularly referred to as ‘phosphorescence’) – the water glowing brightly wherever there was movement – in the waves breaking on the shore, in ripples in the water and wherever people played in the water.
All of this, from Phil's experience, resulted in a "Blue Tide" (via ScientificAmerican.com)
When plankton called dinoflagellates grow too numerous near shore, the single-celled algae can stain the water a reddish-brown, causing so-called red tides that are often toxic to people and fish alike. Certain dinoflagellates species also produce bioluminescence, and when night falls at the beach, the teeming algae can make the shallows glow an electric blue, as captured here by photographer Phil Hart in the Gippsland Lakes in southern Australia.Out at sea, dinoflagellates use bioluminescence as a sort of "burglar alarm": when disturbed, the plankton flash or light up, essentially creating a glowing trail that leads right to their assailant. This silent signal alerts predators higher up in the food chain about the dinoflagellates' nemesis. "[The burglar alarm] is a scream for help," Widder says. "The best chance you have when you're getting attacked is to attract something bigger than what is eating you."
Here are some of Phil's photos of this event. As always, click to expand:
If you want to see some more of these photos, here is a gallery from Phil