Tuesday, 14 January 2014

Captured by the beauty of an algal net


What's the most interesting and beautiful thing in this picture? The gorgeous water lily flowers, the Purple Strife in our floating islands or the Guilfoyle-designed garden landscape surrounding the Nymphaea Water Lily pond in Royal Botanic Gardens Melbourne. No, you have to look beyond the islands. And this is what you'll see...


To the untrained eye this algal mass looks like any other. To the trained eye, well pretty much the same. That is until you get up close. Close enough to pull some from the water, tease it apart in your hand and then, suddenly, all is revealed.

The all is a brittle green net. This is Water Net, Hydrodictyon reticulatum, a green alga. Most of the algae around in our lakes at Melbourne's Royal Botanic Gardens are either microscopic (e.g. the blue-green algae colouring the Ornamental Lake) or consist of unbranched or branched filaments. Like most trees, most algae don't once they've branched (I say most trees because we have a re-connection in one of our oaks, where a branch has grafted itself onto another branch).

Take a look at these pictures by Chris Carter, of Water Net in Thrapston Lake, Northamptonshire, in the UK. He is one the world's best phycophotographers (a word I've just made up) in the world.


The first picture shows a close-up of the net, with each side of the pentagon or hexagon a single algal cell. This is a mature Water Net. The next has a baby net overshadowed by just one interconnection of a parent net. The final image steps back a little so you can see what's going on. Look for the Milky Way like smear of green from top right to middle bottom - that's a baby net, released from inside just one of the cells of the parent net. Isn't (algal) life wonderful.

Water Net is weedy alga, common in irrigation ditches and small ponds like ours. It can be a major pest, clogging waterways and interfering with fisheries. But you have to admit that close-up and under water, it's quite attractive. There are five species of Hydrodictyon but the common, weedy, one is Hydrodictyon reticulatum. That's what we have in the Royal Botanic Gardens.

When I grabbed a handful from the lake yesterday the alga was a little discombobulated, probably due to old age. This next image was taken with a clunky digital phototube I have sitting next to my computer. I'm sure Chris Carter could turn even this into a work of art!


For more of Chris Carter's photographs buy, beg or borrow The Freshwater Algal Flora of the British Isles 2nd Edn (the three images above come from the CD at the back), or find them and everything else you wanted to know about algae in Algaebase. There is even a 3-D picture in both locations, which you view with those funny red and blue glasses. Enjoy...

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