Save the Fen Raft Spider From The Blast

The Fen Raft Spider (Dolomedes plantarius) is not an aquatic spider--there’s no such creature. However, they aren’t aquatic in the same way a Water Strider isn’t aquatic. Just because you can’t swim doesn’t mean you have to get out of the pool—or rather, off the pool. They skate on top, using surface tension to float across the bogs and swamps; hence the name “Fen Raft”.These spiders are found throughout in wetlands throughout Europe, with a fairly spotty distribution. They do not build webs to hunt, preferring to wait on a stem with their front legs touching the water’s surface. When they feel a vibration, BOOM! Dinner is served. Main courses typically include aquatic insects, water striders, and less frequently, fish, like our surprised friend shown above.The water also comes in handy when a male Fen Raft Spider wants to woo the ladies. Courtship involves drumming the water until the couple meets, when they both begin to bob slowly to each other. Mating is quick, likely because it is not unheard of for the male to become a protein source. After laying the eggs, the female carries the egg sac under her fangs for about three weeks. After hatching, the young spend a week growing up in a web-nest that’s constructed and guarded by mom. It seems that wetlands are disappearing everywhere, and therefore, so are the Fen Raft Spiders. The remaining wetlands are getting more and more pollution problems, and all evidence suggests that these spiders require clean water. There’s certainly hope though. Britain has pulled out all the stops trying to protect their two populations from dying out, and frankly, it seems to be working. It's one of Europe's largest and rarest spiders, it feeds on fish caught as it floats menacingly on streams and canals - and it's thriving in Wales. One of only three UK populations of the rare fen raft spider has been observed on a waterway in South Wales - sparking intrigue among scientists about how the unusual species arrived in this part of the UK. Until recently, the "fishing" spider - which is around 3 in. long and uses tiny hairs on its legs to glide over the surface of water was found only on fens in Suffolk and Norfolk, but seven years ago, one of the arachnids was spotted at Llandarcy, near Neath. Now a population of them has been found on the Tennant Canal at Pant-y-Sais Fen, near Jersey Marine, Neath that allowing producers of a new wildlife documentary to obtain rare footage of one. The spider has a black or brown body, over an inch long, with white or cream stripes down its sides. It is known as a fishing spider because it has hairs on its legs that allow it to glide across the water’s surface to grab prey. It has a 7cm leg span. The spider (Dolomedes plantarius) gets its popular name from the way that it leans over pools on a plant and dangles its front legs on the water’s surface to pick up vibrations from approaching prey, mainly pond skaters and dragonfly larvae, sticklebacks and tadpoles. These Fen Raft spider are currently or recently in Wales. The spider is officially an endangered species. It is protected under the Countryside and Wildlife Act. The species is widely distributed on the continent but, like many wetland species, it is declining rapidly as a result of wetland destruction and degradation. Already an extreme national rarity, the fen raft spider population in the UK is declining further. If you are in Europe if you go there and you find a Fen Raft Spider is suffering, help it out because they help us a lot by devouring insects that can harm us that can come to the U.S., so please help!

The Future

To assess the response of D. plantarius to the changes in management on the Pevensey Levels, and to monitor changes in the extent and status of the population, Natural England are developing a long-term population monitoring program for the area.

In the medium term, sea level rise must be seen as a potential threat to the Pevensey population, the greater part of which is on the lowest-lying Levels that were reclaimed from salt marsh in the Middle Ages.

The South Wales Population

In May 2003 D. plantarius was discovered along a short section of the bank of the disused Tennant Canal where it flows through Pant-y-Sais NNR, east of Swansea. In common with the English sites, this a lowland water-body fed by neutral to alkaline, base-rich water. Open, stiff-leaved tussocks of Carex paniculata (tussock sedge) provide the main structure for nursery-web construction although webs are also found in Glyceria maxima. Survey work suggests that the spiders are much less abundant in what appears to be very suitable fen vegetation in the immediately adjacent Pant-y-Sais Reserve. They appear to breed there in some years but not in others, probably limited by the small number of turf ponds that hold water in dry years. D. plantarius also occurs ca 2.5km further west along the course of the Tennant Canal, where it runs in Crymlyn Bog NNR. The full extent of the population at this site is not yet known because the terrain makes survey work very difficult.

The future for D. plantarius conservation in the UK

D. plantarius is intrinsically very vulnerable to extinction because it is restricted to only three sites, at one of which its population is extremely small. Its Species Action Plan, first produced in 1999, seeks to address this issue with the following ambitious targets for its future status:

• an increase the overall range of D. plantarius at Redgrave & Lopham Fen to 13 Ha of habitat occupied 3 years in 5 by 2010 and to 65 Ha by 2020 and


• the number of sites with sustainable populations of D. plantarius should be increased by six by 2010. By 2020 the total number of sites with sustainable populations should be increased to 12.

Despite the slight increase in range at Redgrave and Lopham Fen since 2006 (above) both of these targets are most likely to be met by deliberate trans-location to new sites - both within the Redgrave and Lopham Fen nature reserve complex and more widely in both East Anglia and Southern England. Research evidence (i) that D. plantarius has a very low propensity to disperse and (ii) that there has been a significant decline in genetic diversity in the Redgrave and Lopham Fen population since 1992, suggests that establishment of new populations is likely to be essential to ensure the long-term future of this species in the UK. Natural England, the lead organization for the Action Plan for this species, are committed to a trans-location program provided that it can meet the criteria laid down in the IUCN/JNCC guidelines for trans-location. If all the appropriate criteria can be met, trans-location will begin in England in 2010. In Wales, CCW wish to undertake more survey work before making any decision on whether trans-location is necessary or appropriate.

During 2008 and 2009, as part of the evaluation process, survey work is underway to check that our current understanding of the UK distribution of D. plantarius is correct and that populations have not been overlooked or misidentified. Potentially suitable wetland sites are being surveyed for D. plantarius and sites where D. fimbriatus has been recorded, particularly those with atypical habitat for this species, are being checked to ensure that the species has been correctly identified.

At the end of 2009 the evaluation process will be reviewed and a final decision will be made on whether to go ahead with the trans-location program in 2010. In preparation for this possibility, techniques for rearing newly-hatched D. plantarius in captivity are being tested at the John Innes Centre Insectory, Norwich, during 2008/09. If the trans-location goes ahead, it is likely to use immature spiders, reared from egg sacs brought in from the wild to achieve very high survival rates. The mothers of these broods will be returned to the wild where they are likely to produce a second brood. If very high survival rates can be achieved, a proportion of the captive immature will be returned to supplement their natal populations whilst the remainder will be used to establish new populations. Research currently in progress will be used to decide whether to use spiders of single or mixed provenance at the new sites.
My Plan:
My plan is to help stop wetland destruction and persuade people in the area who are killing the Fen Raft Spiders to leave them alone! I will do this by having assistance from the scientists who are studying the spiders to block any chaos that can harm the Fen Raft Spiders and continue observing or analyzing more to find ways to try to increase in special breeding programs to have a chance to make them off that endangered species list. I don't care if it is in U.K. not in the U.S., I will still protect them because I think that every species are created equal and we have to conserve even for the ugly one like the spiders. I don't think they are ugly, but unique in a way. When I am an adult, I will maybe go to Europe and help scientists, and researchers to protect the Fen Raft Spiders from danger. I can even

observe them myself to see if they are new ways to save them in the future from extinction. We can donate money to programs that are conserving the Fen Raft Spiders because it is only exist in Europe and we don't want an unbalanced ecosystem as well. The people and I should contribute our time to help the Fen Raft Spiders thrive to be not endangered in the future by having people who are interested by knowing knowledge about them, volunteer, and agrees with me that we need to protect this species to not make the ecosystem unbalanced!

APA Citation:
Smith, H. (2009, October 8). welcome to the web site dedicated to the fen raft spider dolomedes plantarius (clerk) . Retrieved from http://www.dolomedes.org.uk/index.html