This report provides the results of a terrestrial invertebrate survey in light of Natural England’s proposal to enlarge the Mucking Flats and Marshes Site of Special Scientific Interest (SSSI). This report details the results of a terrestrial invertebrate assessment found in Tilbury Fort Marshes, a network of brackish watercourses and dry grassland compartments surrounding Tilbury Fort in Tilbury, south Essex. The survey was undertaken using pitfall trapping and active sampling methods. The survey produced a total of 388 species, 63 of which had a conservation status, including seven Section 41 Species of Principal Importance.
Whole invertebrate assemblage analyses using Pantheon valued the importance of saltmarsh and brackish pool & ditch habitats particularly highly and found the saltmarsh & transitional brackish marsh invertebrate assemblage to be in particularly favourable condition.
Although the invertebrate interest of the grassland was much lower than expected due to overgrazing by horses, the site supported a modest pollinator fauna, including two species of Section 41 bumblebee. Herbivore dung was also an important resource for a number of species of high conservation value.