Killer Algae (3 of 20)

Meinesz is an expert on the marine life of the Mediterranean.
He knew that among the dozens of plants that live in it there is one key plant that is fundamental to the sea's ecosystem.
It normally covers large areas of the seabed.
It 's a dark, grey/green sea grass called possidonia.
Possidonia is a plant which provides food and shelter for a huge variety of fish and invertebrates, but that day as Alexandre Meinesz dived, nothing was as he expected it to be.
The water was very clear.
The sun was shining and the visibility was good.
Then I saw straightaway that the seabed was bright green.

I said to myself this isn't possible, there shouldn't be any brilliant green seaweed here.
Where Meinesz had expected to find the usual variety of Mediterranean sea life all he could see for hundreds of metres was a dense and bright green mat of weed he'd never seen before.
As he studied the extraordinary new plant he realised it was a giant variant of a tropical algae called caulerpa taxifolia yet how could a tropical plant survive in the colder waters of the Mediterranean?
He decided to try and find out what was going on.
Back in the laboratory he compared the taxifolia with other specimens of the same family of algae from around the world.
: I have a few specimens that I collected myself several decades ago in the Red Sea and here is Tahiti in Polynesia.
They are all small, whatever depth they come from not very long, not very wide and the runners are always very thin, so I realised straightaway that what was growing in the Mediterranean was something absolutely exceptional, that had never been seen before.