A rare water loving spider big enough to catch vertebrates such as fishes and newts, by walking or diving in its aquatic habitat, has been given a conservation boost, with thousands of spiderlings hatched and nurtured in 10 British zoos and aquariums to be released into their wild fenland habitat.
The fen raft spider (dolomedes plantarius) is listed as Vulnerable on the IUCN’s Red List of Threatened Species and as Threatened in the UK Red Data Book. It is found in only three sites in Britain – in Norfolk, East Sussex and South Wales, almost certainly because of major losses to its wetland habitats. However, thanks to the help of the zoo community the fens of East England could start seeing more of this spectacular creature. The aim of the programme is to secure the future of this species in the UK by increasing the number of populations from 3 to 12 by 2020.
The zoos, all members of the British and Irish Association of Zoos and Aquariums (BIAZA), are acting as foster parents to a total of 2450 fen raft spiderlings, which are being reared in the zoos for two months until they are strong enough to face the outside world and then released back into their natural habitats.
Ian Hughes of Dudley Zoo, who has helped co-ordinate the zoos’ efforts, said: “The work these zoos are doing is vital not only to raise awareness of the plight of the fen raft spider, but to show how collaboration between zoos and other partners can have a huge impact on the future survival of our native species.”
ZSL London Zoo is one of the partners involved in the conservation efforts, and received 200 tiny spiderlings this week. Invertebrate keeper Jeff Lambert says: “These iconic spiders walk on water and use their legs to detect ripples on the surface and catch their prey – in effect the water is their web. It’s a great privilege for ZSL London Zoo to help rear and re-introduce fen raft spiders back into their natural habitat.”
The work the zoos are doing is part of a much wider partnership led by Natural England – the Fen Raft Spider Species Recovery programme. Using techniques devised by project co-ordinator Dr Helen Smith and the John Innes Centre Insectory, the foster parents rear spiders in individual test tubes for several weeks before they are released.
The spiderlings that are being reared for release come from the very small natural population on Suffolk Wildlife Trust’s Redgrave and Lopham Fen reserve. Rearing them in captivity increases their slim survival chances in the wild to over 90%. They are then released back on the Fen and to new sites in East Anglia.
Translocation of the spiders to establish the first new population in the wild was started in 2010 following several years of work to ensure the likely success of the project.
In 2011, a partnership of BIAZA zoos willing to help with the captive rearing was created. Dudley Zoo, Chester Zoo, Chessington World of Adventure and the Lakeland Wildlife Oasis each fostered between 200 and 400 spiders, supplied by Helen as ‘test-tube ready’ 1-2 week old spiderlings.
The spiderlings released in 2010 are breeding successfully for the first time this summer and almost 10,000 spiderlings reared and released in 2011, with the zoos’ help, are expected to breed for the first time next summer.
Since then the fostering process has been modified and the programme has grown. This year more spiderlings will be released at these sites and one more new population will be established in the Broadland.
Mr Hughes added: “The captive rearing of spiderlings is very labour intensive, primarily because of the need to maintain them in individual containers to avoid cannibalism, but thanks to the collaboration between BIAZA zoos and the other programme partners, all the foster parents have so far achieved high survival rates, giving real hope for the fen raft spider.”
The ten zoos involved are: Dudley Zoo (co-ordinating), Bristol Zoo, Beale Park, Chessington World of Adventures, Chester Zoo, The Deep, Lakeland Wildlife Oasis, ZSL London Zoo, Reaseheath Agricultural College and Tilgate Nature Centre.
Other partners are: Natural England, The Norfolk, Suffolk and Sussex Wildlife Trusts, The Broads Authority, RSPB, the University of Nottingham, Buglife and the British Arachnological Society, with funding from Natural England, the Broads Authority and the BBC Wildlife Fund, as well as from a host of volunteers.
Posted on Environment Times Online on 21st August 2012.