The pond life in the acidic pools of Chailey Common
Posted by Graeme Lyons , Saturday, 16 September 2017 06:45
Last Saturday I ran a course for the Freshwater Habitats Trust's PondNet project up at Chailey Common. I've just got around to identifying everything. We only really had time to sample four ponds in detail but we also managed a quick diversion to a number of other sites around the common. We started with a couple of small man-made ponds full of Bog Pondweed, Floating Club-rush and Marsh St. John's-wort. These ponds are very acidic, with dark peaty water so we expected to find the more specialist aquatic invertebrates. I told everyone we would see the distinctive Notonecta obliqua, the most distinctive of our four backswimmers and it was indeed the commonest bug in the pools. We actually recorded all four of our backswimmers in these four pools. In the above image one of our (around 40) species of water boatman (this one of two species of Hesperocorixia recorded in this one pond) can be seen in the background. Most backswimmers are much bigger than water-boatmen, it helps to be bigger than things that you eat!
Nice to see some Marsh St. John's-wort and Floating Club-rush.
The first pool had two species of Dytiscus in and it was nice to be able to key these out in the field. Thanks to Fran Southgate for this photo of the commoner Dytiscus marginalis on the left and Dytiscus semisulcatus on the right. However the nationally scarce Hydrochus angustatus was perhaps the most interesting being a species I have not recorded before.
One pool had an adult 13-spot Ladybird in it and I'm pretty sure that this is also the larva but it looks a little bedraggled.
This is the most Floating Crystalwort Riccia fluitans (one of our few aquatic liverworts) I have ever seen. You usually see a few little plants floating on the surface, not a huge mass like this!
We called in and had a look at the Marsh Gentians on Romany Ridge that have responded to the grazing there. A great success.
But the highlight for me has to be a diversion to Lane End to look for the Mud Snails that were relocated there last year after not being recorded for many years. The dried up woodland pool they were found in looked quite unsuitable for anything else. In fact next to nothing else was found in there but we did see two Mud Snails! This is typical for this scarce species. It was very dark and dingy in the woods by this time so apologies for the photo. Note to self: next time look for this first. Look at the state of the kit!
A big thank you to everyone who attended. a full species list will be send to the Freshwater Habitats Trust and the records synced with the SxBRC as always (I've nearly entered 10,000 records already this year!)
So, here is the full list which includes 14 aquatic bugs, 15 aquatic beetles but only two molluscs (acid sites are not so good for shell building). Here are my records for the day including a few random things like Devil's Fingers that are nothing to do with aquatic life.
Taxon group | Species |
annelid | Erpobdella testacea |
annelid | Helobdella stagnalis |
annelid | Theromyzon tessulatum |
crustacean | Asellus aquaticus |
crustacean | Crangonyx pseudogracilis |
flowering plant | Water-plantain |
flowering plant | Downy Birch |
flowering plant | Callitriche sp. |
flowering plant | Star Sedge |
flowering plant | Floating Club-rush |
flowering plant | Marsh Gentian |
flowering plant | Floating Sweet-grass |
flowering plant | Marsh St John's-wort |
flowering plant | Yellow Iris |
flowering plant | Sharp-flowered Rush |
flowering plant | Bulbous Rush |
flowering plant | Compact Rush |
flowering plant | Soft-rush |
flowering plant | Water-purslane |
flowering plant | Purple Moor-grass |
flowering plant | Creeping Forget-me-not |
flowering plant | Small Pondweed |
flowering plant | Bog Pondweed |
flowering plant | Lesser Spearwort |
flowering plant | Ivy-leaved Crowfoot |
flowering plant | Thread-leaved Water-crowfoot |
flowering plant | Grey Willow |
flowering plant | Branched Bur-reed |
fungus | Devil's Fingers |
insect - beetle (Coleoptera) | Acilius sulcatus |
insect - beetle (Coleoptera) | Agabus bipustulatus |
insect - beetle (Coleoptera) | Anacaena limbata |
insect - beetle (Coleoptera) | Anacaena lutescens |
insect - beetle (Coleoptera) | Water Ladybird |
insect - beetle (Coleoptera) | Dytiscus marginalis |
insect - beetle (Coleoptera) | Dytiscus semisulcatus |
insect - beetle (Coleoptera) | Haliplus ruficollis |
insect - beetle (Coleoptera) | Haliplus flavicollis |
insect - beetle (Coleoptera) | Helochares punctatus |
insect - beetle (Coleoptera) | 13-spot Ladybird |
insect - beetle (Coleoptera) | Hydrobius fuscipes |
insect - beetle (Coleoptera) | Hydrochus angustatus |
insect - beetle (Coleoptera) | Hydroporus pubescens |
insect - beetle (Coleoptera) | Ilybius fuliginosus |
insect - beetle (Coleoptera) | Laccophilus minutus |
insect - beetle (Coleoptera) | Noterus clavicornis |
insect - dragonfly (Odonata) | Southern Hawker |
insect - dragonfly (Odonata) | Migrant Hawker |
insect - dragonfly (Odonata) | Emperor Dragonfly |
insect - dragonfly (Odonata) | Downy Emerald |
insect - dragonfly (Odonata) | Large Red Damselfly |
insect - dragonfly (Odonata) | Ruddy Darter |
insect - dragonfly (Odonata) | Common Darter |
insect - moth | Brown China-mark |
insect - moth | Broom Moth |
insect - true bug (Hemiptera) | Corixa punctata |
insect - true bug (Hemiptera) | Eurygaster testudinaria |
insect - true bug (Hemiptera) | Gerris gibbifer |
insect - true bug (Hemiptera) | Gerris odontogaster |
insect - true bug (Hemiptera) | Gerris thoracicus |
insect - true bug (Hemiptera) | Hesperocorixa castanea |
insect - true bug (Hemiptera) | Hesperocorixa linnaei |
insect - true bug (Hemiptera) | Hesperocorixa sahlbergi |
insect - true bug (Hemiptera) | Nepa cinerea |
insect - true bug (Hemiptera) | Notonecta glauca |
insect - true bug (Hemiptera) | Notonecta maculata |
insect - true bug (Hemiptera) | Notonecta obliqua |
insect - true bug (Hemiptera) | Notonecta viridis |
insect - true bug (Hemiptera) | Plea minutissima |
insect - true bug (Hemiptera) | Sigara limitata |
liverwort | Floating Crystalwort |
mollusc | Musculium lacustre |
mollusc | Omphiscola glabra |
spider (Araneae) | Pachygnatha clercki |
spider (Araneae) | Trochosa ruricola |
spider (Araneae) | Pirata latitans |
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