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German Science Weekly Highlight-17

A Happy Catastrophe in the Baltic Sea


If you get out your map of Germany, and peer just north of Kiel – on the shores of the chilly Baltic Sea – in fact, at coordinates 54° 41´ north, 10°12´east – you’ll find a regular old estuary, where sea water mixes with fresh water, near the village of Maasholm. It’s a pretty inauspicious place. Pale blue water. Fishing boats rocking at the pier. A horse neighs in the background.

Not the kind of place that you would expect a disaster.

And not a whole lot of disasters have happened there. Except for one.

In the summer of 2003, the Baltic Sea heated up. Down in the estuary near Maasholm, huge amounts of plants under the sea were killed. Many people probably never noticed these plants died. But a group of scientists did – researchers from the Max Planck Institute for Limnology in Plön, near Kiel, a short drive south of Maasholm. Limnologists study inland waters, and it just turns out, that these researchers themselves had laid down this sea grass, as part of experiments on bio-diversity and genetic diversity (we’ll talk about genetic diversity in a moment). After nature came and exterminated the sea grass en masse, the researchers had a very interesting question on their hands: how will the ecosystem, in the place these plants grew, recover?

They discovered something remarkable: that genetic diversity helps an ecosystem recover from disaster. Now, it’s already known that bio-diversity helps. Let’s make clear what the difference between these two kinds of diversity is. Bio-diversity , as you probably know, refers generally to having lots of different kinds of living organisms – in the case of an estuary, seaweed, sea stars, small crabs, and many more, like in the picture on the right.

Fauna einer Seegraswiese

Genetic diversity means having lots of different kinds of otherwise similar organisms. One example in history, where a lack of genetic diversity may have led to a true disaster – hundreds of thousands of people dying – was the Irish Potato Famine of the mid 19th century. There were so few genetic strains of potato in Ireland that when a virus came, it wiped out almost instantly all the potatoes – and the staple food of the Irish.

Because of climate change, there seem to be more and more extreme events happening out there – heat waves, floods, storms. So for natural preservationists, it’s useful to know how they can rebuild their populations, after disaster strikes. Otherwise, they ecosystems they’re preserving may never recover. Keeping genetic diversity may now be one important part of their work. Click below and Dr. Thorsten Reusch of the Max Planck Institute in Plön will tell you about how this happy catastrophe might help prevent unhappier ones.

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