Megadeath

A day of trudging through harvested wheat fields to monitor the extensive system of ditches which form the field boundaries. Like much of the fens, the water levels are determined by a complex system of sluices and pumps, and we're never sure how much water there will be in the ditches. When we arrived we were disappointed to see that the main drain was largely completely dry, apart from a couple of pools near the pump house where we disturbed a rather happy little egret, no doubt feasting on the trapped fish and invertebrates.

We had the rather unusual experience of walking along the drain bottom, crunching snail shells underfoot. At one inlet the bottom of the drain was covered with a thick layer of greater pond snail and ramshorn's shells - death and destruction on a massive scale. Fortunately many water beetles and other wetland invertebrates can fly, and are able to escape as water levels decline, finding refuges elsewhere in the local ditches. But snails are not very mobile, and this is why they are so badly affected by any form of sudden and intense management.

Luckily a proportion of the drains in the western part of the site held shallow water, and we found a good range of plants and insects, including a new site for the endangered species, grass-wrack pondweed. This was recorded from nearby rivers and larger drains a few years ago, and I suspect it colonised this new location when water levels were very high during the spring, causing water to back up from the main rivers. So at least the wet weather has had some beneficial effect!