Below are brief descriptions of several species to look out for in the water around the estuary. Further detailed information sheets and images can be viewed by following the links.
American tingle or oyster drill (Urosalpinx cinerea) - First recorded in 1927, its distribution in the UK appears to be limited to the Kent and Essex coasts. Yellowish, orange or grey in colour (sometimes with irregular brown marks), it has a tall conical shell up to 4cm high and 2cm broad, with a shaply pointed spire and up to eight rounded whorls bearing prounounced ridges and ribs. It is a major pest to the commercial oyster industry, preying heavily on both native and introduced oyster species. It feeds preferentially on oyster spat and has been reported to decimate stocks in some estuaries. Please report any sightings (along with a photograph), using our on-line form.
Carpet Sea Squirt (Didemnum vexillum) - First recorded in a Welsh marina in 2008, this native of the Pacific Ocean, is now present in Kent at Herne Bay. Capable of forming very large colonies, it literally 'carpets' the hard structures upon which it grows. Its fast growth threatens our fishing industry, shellfish growers and our marine habitats. Species Alert! Sightings(along with a photograph) should be reported as soon as possible at: http://www.brc.ac.uk/risc/alert.php?species=carpet_seasquirt
Chinese Mitten Crab (Eriocheir sinensis) - Originally from eastern Asia, this large crab is believed to have been present in the Thames since 1935. Olive green in colour, its most distinguishing features are its hairy claws. The crab is a voracious predator, that consumes a range of invertebrate species and the eggs of fish. It also burrows into river banks, causing erosion and eventually bank collapse. Please report any sightings (along with a photograph), using our on-line form.
Floating pennywort (Hydrocotyle ranunculoides) - First naturalised in 1990, as a result of discarded plants from garden ponds. This freshwater plant can grow up to 20cm per day, forming thick mats which impede water flow and cause deoxygenation. It is an offence under schedule 9 of the Wildlife & Countryside Act to plant or otherwise cause this species to grow in the wild. Please report any sightings (along with a photograph), using our on-line form.
Killer shrimp (Dikerogammarus villosus) - This highly invasive species has spread from South-East Europe and has only recently been found in the UK. A voracious predator, it kills a number of native species, including young fish and can significantly alter ecosystems. Species Alert! Sightings(along with a photograph) should be reported as soon as possible at: firstname.lastname@example.org
Orange-tipped sea squirt (Corella eumyota) - Up to 8cm in length, it lies flat with its exhalant orange tinged siphon slighlty to the right. Its tunic is translucent and smooth, whilst its gut forms a smooth curve around its hind end. Its origin lies in the Southern hemispshere and since its arrival in the UK, it has spread rapidly. Individually its impacts are small, but as dense clumps it could affect the abundance and habitat of cultured bivalves, as well become a serious fouler of mussel and oyster culture gear. Please report any sightings (along with a photograph), using our on-line form.
Red ripple bryozoan (Watersipora subtorquata) - First detected in the UK in 2008, its native range has yet to be determined, but it is becoming common around the world on cool-temperate coasts. It's arrival in the UK is likley to have been by leisure craft, since its first occurrences were in marinas. It is capable of forming very large colonies, which are likely to have considerable effect on pre-existing sessile communities through overgrowth. Relatively resistant to copper-based antifouling treatments, it may enable other less resistant species to colonise hulls and potentially exacerbate general fouling and the spread of other non-native species. Please report any sightings (along with a photograph), using our on-line form.
Image Gallery: http://www.exoticsguide.org/watersipora_subtorquata
Veined rapa whelk or Mangrove oyster (Rapana venosa) - Currently not believed to be established in the UK, though several were caught in the North Sea in 2005. Growing up to 18cm in length, this whelk preys voraciously on a range of marine invertebrates, including soft sediment burying bivalves, snails, oysters, mussels, clams and crabs. It has been predicted that the successful establishment of this species in the UK, may threaten the bivalve industry. Please report any sightings (along with a photograph), using our on-line form.
Wakame or Japanese Kelp (Undaria pinnatifida) - A large brown seaweed, whose stipe has very wavy edges or rufles at its base, giving it a corrugated appearance. Native to the cold temperate areas of Japan, China and Korea, it was first recorded in the UK in 1994. It may compete for space with native species and in high levels of abundance, foul jetties, vessels, moorings and buoys. Please report any sightings (along with a photograph), using our on-line form.
Wireweed (Sargassum muticum) - Native to the shores of the north-western Pacific, wireweed was first identified on the Ilse of Wight in 1973. It is a highly distinctive seaweed, olive-brown in colour and often over 1m in length. It competes with native seaweeds and seagrasses and is a nusiance to harbours and marinas, where it can become entangled in boat propellers. Please report any sightings (along with a photograph), using our on-line form.