Saturday, 14 March 2009

Climate change turn algae into sludge

Photo: A unicelllar alga called Cosmarium, a desmid that grows in freshwater ponds

OK, back to science for a while. One of the things I try to do is keep up with the latest botanical discoveries.

I do this by skimming popular science magazines such as New Scientist, and the front (relatively easy to read) pages of Science and Nature. I also check on a few web sites that keep tally of recent publications - a good one is EurekAlert!, and I do a regular search on plant sciences.

There are plenty of other places, including our own newspapers and media websites such as ABC Science.

So, what's this about climate change and algae. It's really about their nutritional value - I use the term 'sludge' as a desciptor for useless material rather than a technical term in waste management!

In a report from the Netherlands Institute of Ecology, it seems that increased carbon dioxide levels may well lead to greater algae growth, but those algae may be poor food for the tiny water animals that consume them. This is bad news for not only the tiny water animals, but the fish that eat them and the animals (i.e. you, I and other bigger folk) that eat the fish.

The study used mostly unicellular algae - ones that you can't see unless they form discolouring blooms on ponds and the Darling River - finding that they they took up more carbon (which is prseumably a good thing for the environment) but contained less phosphorus (which is a bad thing for those things living in the environment).

As usual it is the subtle effects of change we have to watch. There are so many interactions and interdependencies in our natural world that adjusting just one of the settings can have unexpected consequences.

On the other hand there is usually some great buffering capacity built into ecosystems, with redundancy generally the rule (e.g. a bunch of different plants that use bacteria to fix nitrogen rather than just one in each bushland patch). But how much 'redundancy' is needed to adapt to the changes we are about to experience and where are the so-called tipping points. Generally, 'who knows' is the answer.

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