The Weekend Biologist: Total Ecosystem Collapse

The title is an oft used phrase "borrowed" from the Punkbirders (see here for example). This phrase, I thought, was unimaginable. We often hear about certain species or groups being wiped out of an area but there are normally other things that survive perfectly well. I can also imagine that there may be news stories of such ecological disasters (real ones, not the Daily Mail trying to over-explain something). What I never imagined was that I would see such an event myself and nor did I imagine it to happen in an area so close to my heart. Walking round yesterday was, to say the least, upsetting. The following photos are from Currymoor in Somerset. I cut my Natural History teeth here in an age before instant internet IDs and good field guides. This is where I learned to observe and identify species using poorly illustrated and narrated guides and keys. This is where I realised that birds are not the only things worth looking at. This is an area with 20+ species of Odonata including Variable, White-legged and Large Red-eyed Damselflies, Scarce Chaser and Brown Hawker together with countless rare and interesting species of groups I never had time to study (loads of good plants for instance). I have also seen over 120 species of bird here. I may be being pessimistic but all of that seems to be gone now and unlikely to return in the near future.

So what happened? You may remember in this post I showed a picture of some flooding in early May. They were not able to pump that water away for a while as the river was still breaking its banks due to the high rainfall. The murky water, relatively high temperatures and other factors led to some quite serious hypoxic condition in the water that then led to most things rotting. It got so bad that they were unwilling to pump water off so as to avoid polluting the river, making everything worse. The water stayed for over a month and there is still plenty there. Almost everything is dead. I saw just a few plants that were making some sort of comeback and there were a few of the commonest birds about (BHGs, Grey Herons, Woodpigeons). Most obvious was the lack of aquatic plants and the number of dead crustaceans/molluscs - see below). It looks like the entire ecosystem collapsed from the bottom up, starting with the plants. What was obvious was that the Water Snails had died in their shells and had not even rotted but their bodies were drying out where they were. There was almost a complete lack of invertebrates as well - just they very occasional dipteran really. I reckon that the Odonata are stuffed for this year and will have to recolonise. The last time we had summer flooding, several species disappeared and took over 10 years to return.........

Generally gutted and feeling pretty empty. Think I'm exaggerating? See below. If I cheer up, there were some rays of light as well and I'll post some photos.