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Surveys of Invertebrate Prey of Waders in Estuaries

We have experience in surveying all common wader prey in UK estuaries. These include:

Ragworm (Hediste diversicolor or Nereis diversicolor)

Catworm (Nephtys hombergii)

Lugworm (Arenicola marina)

Tubificid oligochaete worms (e.g. Tubificoides benedii)

Mudsnail (Hydrobia ulvae)

Peppery furrow shell (Scrobicularia plana)

Baltic tellin (Macoma balthica)

Tellina tenuis

Mussels (Mytilus edulis)

Cockles (Cerastoderma edule)

Corophium volutator (an amphipod crustacean)

Brown shrimp (Crangon crangon)

Shore crab (Carcinus maenas)

Wader Prey Survey Methods

Aquatonics Ltd can advise on the most appropriate survey methods for wader prey. Issue to be ocnsidered include:

Whether sampling is required down to low water spring tide level at all sites

Number of replicate samples required, or whether to spread sampling effort more widely

How often to repeat the survey, for example are data required prior to and after the overwintering period?

Whether to measure biomass and if so whether to measure wet, dry or AFDW

Tidal height and wader prey

Tidal height is an important factor determining benthic communities, but natural selection has ensured that peak densities and biomass occur at different heights on the shore for different species. For some important bird prey such as ragworm and mudsnails (Hydrobia ulvae) densities and biomass are usually highest on the upper to upper mid shore. Densities of juveniles of many species are often highest on the upper shore, which may act as a nursery area for species such as Baltic tellin (Macoma balthica) and cockles (Cerastoderma edule). Information on the distribution of individual species is contained in some standard textbooks, for example “A Student’s Guide to the Seashore” (Fish and Fish, 1989) and “Intertidal Ecology” (Raffaelli & Hawkins, 1996). Some research papers have diagrams of occurrence down the shore, for example in Morecambe Bay (Anderson, 1972) and in the Towy estuary (Howells, 1964). These confirm the view that at any site each species has its own unique distribution down the shore, and that for some species the distribution of adults and juveniles down the shore may be different. There will also be differences between shores, mainly due to the distribution of different particle size sediments substrates and also due to differences in water-retention, redox discontinuity, salinity etc.

Very few key wader prey have peak densities at or below Mean Tidal Level. The most obvious examples are catworm (Nephtys hombergii) and the bivalve Tellina tenuis. Most other species have maximum densities (and biomass) either over a very wide range of tidal heights (eg cockles, Cerastoderma edule) or in the mid to upper shore (eg Hydrobia ulvae, Macoma balthica, Arenicola marina, Nereis diversicolor, Corophium volutator).

REFERENCES

Anderson, SS (1972). The ecology of Morecambe Bay. II. Intertidal invertebrates and factors affecting their distribution. Journal of Applied Ecology Vol 9, 161-178.

Fish JD and Fish S (1989). A Student’s Guide to the Seashore. Unwin Hyman. London.

Howells, WR (1964). The macrofauna of the intertidal soils of the Towy estuary, Carmarthenshire. The Annals and Magazine of Natural History, Vol 13, 577-607.

Raffaelli, D and Hawkins, SJ (1996). Intertidal Ecology. Chapman & Hall. London.

Estuaries, Harbours and Lagoons

Aquatonics Ltd have surveyed most of the major estuaries in England, including the Humber, Thames, Southampton Water and Severn estuary. In addition we have surveyed a wide range of smaller estuaries, ports, harbours and some lagoons. The full list is below:

Axe estuary Beauly Firth Bembridge Blackpool beach Burry Port Chesil Beach Clacton beach Clyde estuary Dart estuary Exe estuary Fal estuary Folkestone harbour Great Ouse estuary Hayle harbour, Lelant Water, Carnsew & Copperhouse Pool Helford Humber estuary Kingsbridge estuary Lulworth Cove Medina estuary

Medway Moray Firth Orwell estuary Otter Plym Plymouth Harbour Portland harbour Portsmouth harbour Taw-Torridge Tees estuary Thames estuary The Fleet Truro river estuary Severn estuary Southampton Water Ventnor beach Wash West Bay beach