Invertebrate survey successes for Cley Marshes

coastal lagoon

Ben Christie sampling lagoonal invertebrates


Our follow-up survey on Norfolk Wildlife Trust’s new marsh at Cley has found five invertebrate species of conservation importance, including lagoon sand shrimp Gammarus insensibilis (legally protected) and mud snail Ecrobia ventrosa.

The Trust commissioned a specialist baseline study on their new land at Cley Marshes when they purchased it in 2014. This was surveying the plants and invertebrates in the site’s ditches, dykes and scrapes.

Since then, the Trust has carried out extensive work on the marsh to convert it from wildfowling ponds to a nature reserve and wanted to repeat the surveys. The plan was to compare with the 2014 baseline and identify any changes resulting from the work.

Twelve sample ditches and lagoons sites from the 2014 survey were re-surveyed for aquatic invertebrates, following the same methodology. For each, we took two dip-net samples to collect a crosssection of the aquatic invertebrates in the water: one in underwater vegetation near the shore; and one reaching out into the depths of the open water.

Ben Christie, our invert specialist said: “By first grouping inverts into taxonomic orders and then using specialist microscope keys for identification, we were able to efficiently identify the specialist communities for every sample site. This allowed both a direct comparison of communities in 2014 and 17, but also showed distributions for five invertebrate species of conservation importance.

“Norfolk Wildlife Trust can now fully assess the benefits of their management on invertebrates as well as the birds and other wildlife who are dependent on them in the food chain.”



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