Protected Species | Freshwater Crayfish & Aquatic Invertebrates
Aquatic invertebrates are ubiquitous in our watercourses and ponds and have been used for many years as indicators of water quality and more recently to assess the impacts of low flows.
The largest freshwater invertebrate in the UK is the crayfish and there is one native species, namely the white-clawed crayfish, also called the Atlantic stream crayfish, Austropotamobius pallipes.
Peak Ecology Director Jonathan Brickland tends to lead on the freshwater invertebrate projects, as he has many years of experience in previous roles with the Environment Agency, Pond Conservation and British Waterways. He is a national expert on freshwater crayfish; in 1996 he set up and, for four years, chaired the National Biodiversity Action Plan Steering Group for the white-clawed crayfish.
The standard survey technique for invertebrates requires a standard pond net used for a three-minute ‘capture’ period followed by a one-minute active search. Identification to family level is possible in the field but samples are usually identified in the laboratory and may be preserved prior to identification; this allows much greater accuracy. Peak Ecology has used invertebrate surveys to study the impacts of river flow management, polluting discharges and to predict impacts of micro-hydro schemes.
The crayfish survey technique is more in-depth; the surveyor must define a survey reach and then identify key areas to concentrate the survey effort within it. Whilst here in the UK there is only one native species of crayfish, there are at least five introduced species, with the American signal crayfish being particularly widespread, therefore the ability to identify the species is essential.
Peak Ecology can undertake crayfish and invertebrate surveys to meet your needs. We can also provide training and do occasionally deliver presentations to interest groups.
If you are interested in any of our services, don’t hesitate to contact us >>
Crayfish | Case Studies
Aquatic Invertebrate Survey – Bakewell
A survey was undertaken to assess which invertebrates were present in a mill race prior to the installation of a micro-hydro electric generating scheme. The standard survey technique was employed but the sub-samples were kept separate and identified to species level. This gave a good understanding of how the microhabitats in the survey area were being used, enabling us to predict the impact of any changes in flow.
White-Clawed Crayfish – Yorkshire Dales
This was a study over a five-year period to determine whether any changes in the white-clawed crayfish population could be attributed to changes in the flow regime in a reservoired catchment. There were issues with regards the volumes of water that could be retained in the reservoir to ensure that adequate flows could be maintained during prolonged dry periods. The study indicated that the crayfish population was expanding and the temporary experimental flow regime was not detrimental to the population.