Surveying for macroinvertebrates

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1 Surveying for macroinvertebrates
PondNet Surveying for macroinvertebrates Adapted from a presentation created by Martin Hammond

2 Aquatic macroinvertebrates in ponds

3 Water bugs Relatively easy to identify
Useful indicators of structural diversity Ecologically important Species respond to vegetation structure, successional stage, water pH, predation pressure Adults mostly in spring and autumn

4 Differences between beetles and bugs

5 Water beetles By far the most speciose group which can be sampled with a pond net Ecology and distribution of species well known Adults can be sampled almost throughout year Distinct assemblages (e.g. acidic peat, fenland drains, pioneers) Some species indicative of ancient wetlands Species level ID tricky for some genera

6 Dytiscidae Hydrophilidae
HIND COXAE Dytiscidae Hydrophilidae

7 Haliplidae Noteridae

8 Other wetland Coleoptera
No strict definition of water beetles Ground beetles, rove beetles etc. associated with water margins outnumber fully aquatic species Reed beetles important indicators of high quality standing waters but many species declining internationally

9 Aquatic molluscs Easy to moderately difficult to ID to species (smaller ramshorns tricky) Pea mussels often excluded – very difficult to ID Low diversity in most ponds and stagnant drains, higher in base-rich waters with moderate flow and varied vegetation structure Overgrown, seasonal, peaty pools & ditches may be important for Mud Snail

10 Snails - a brief overview
Freshwater limpet - Acroloxidae Ram’s-horn snails - Planorbidae

11 Snails with an operculum
Faucet snails – Bithyniidae 17mm River snails – Viviparidae 30mm Valve snails – Valvatidae 15mm Jenkin’s spire snail – Hydrobiidae 6mm

12 Very large + pointed spire
What else could it be? - spire snails without an operculum FAMILY LYMNAEIDAE Radix balthica Very large aperture 12-20mm Lymnaea stagnalis Very large + pointed spire 35-50mm

13 - spire snails without an operculum
What else could it be? - spire snails without an operculum 14-25mm 19-24mm 8-12mm 9-15mm

14 Caddis flies Can be frequent in still water: a large component of the pond fauna overall though there may be few species in individual ponds Scarce in mud/silt: prefer firm substrate or well-structured habitat (stony streams, leaf litter pools, submerged weed beds) Some taxa very small, cryptic and seasonal The widespread Limnephilidae are time consuming to ID to species 198 species

15 True Flies Aquatic fly larvae are widespread, abundant and of huge ecological importance Only a few taxa amenable to sampling with a pond net Soldierflies (Stratiomyidae) are useful indicators of high quality ponds & ditches and have distinctive larvae, identifiable to species Other Diptera such as snail-killing flies (Sciomyzidae) also very characteristic of ponds and ditches.

16 Other groups Leeches fairly easy to ID (live!) but only a few common species. Medicinal Leech stronghold in a few ponds in the New Forest. Flatworms: need to be collected live. ‘Macro’ crustacea (hoglice, amphipod shrimps) – very few common species, more in brackish water.

17 Other groups Mayflies: usually only Pond Olive, occasionally Caenis species. Others in lakes. Alderflies: one common species and counts in two PSYM metrics! Stoneflies: infrequent and usually only one or two species e.g. Nemoura cinerea. More in wave-washed lakes.

18 Other groups Dragonflies and damselflies: very popular, well-recorded group. Adults often very mobile, records of larvae or exuviae needed to prove breeding. Good ecological indicators. Some larvae present all year but sampling in early summer most effective: annual species only present as eggs or tiny larvae in late summer.

19 Now your turn . . .