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27 years on: Seaweeds of The Isles of Scilly are thriving but with a few newcomers
28
Sep
2010
The Isles of Scilly is known to be rich in its marine biodiversity, supporting a wide range of marine life from rare sunset corals to meadows of seagrass, but some of the greatest richness lies in the diversity of its seaweeds and the Isles of Scilly Wildlife Trust has been investigating.
Seaweeds are simple underwater plants which fall into three basic groups; greens, browns and reds. Approximately 600 species are known to occur in the UK, with a third of these being found in Scilly, so some expertise was needed to be able to survey the seaweeds of the area.
Professor Juliet Brodie from the Natural History Museum took part in the last major study of the seaweeds of the Isles of Scilly in 1983, and this year returned to lead a team of Isles of Scilly Wildlife Trust volunteers in an intensive week long seaweed survey expedition. The survey explored both the shores and shallow seas around the islands, investigating a wide range of habitats from exposed shores where Atlantic breakers crash to gravelly tideswept channels where the sea funnels between the islands. Each yielded different species which were sampled for identification back in the field laboratory on St Mary�s.
Professor Brodie�s aim was to look at whether the seaweed flora was much the same as it was reported to be in 1983, or whether any changes could be detected. Since 1983, knowledge of the seaweed flora of Britain and Ireland has developed considerably. The application of molecular data has revealed a number of cryptic species in the flora and resulted in the description of a number of new species, which is reflected in the lists for the 2010 survey.
In these days of climate change and other major threats to the marine environment Professor Brodie reassuringly says, �My initial impression of the state of the seaweed flora is that the flora appeared to be generally similar to what was found in 1983. We have recorded at least 150 species this time and I suspect that number will rise once some of the trickier species to identify have been studied in more detail.�
Many beautiful species were recorded, including red seaweed and a number of rarities, such as pestle weed and bornet�s coral weed. The most striking change is the well-established presence of non-native species also known as �aliens�. Some were there in 1983, such as harpoon weed but others, including wire weed and devil�s tongue weed, both conspicuous and invasive alien species from the Pacific, are well-established but were not recorded in the first survey.
Under Professor Brodie�s guidance, the volunteer survey team sampled and pressed hundreds of seaweeds which will be kept as a record and used for further DNA work back at the Natural History Museum. Angie Gall co-ordinated the survey for The Isles of Scilly Wildlife Trust says, �Once again thanks to a combination of experts and truly dedicated volunteers we have successfully surveyed a group of difficult to identify species and vastly added to our knowledge about the marine biodiversity of the Isles of Scilly. I think everyone on the expedition has come to appreciate the beauty and variety of these simple plants�.
The survey was part of the Isles of Scilly Marine Biodiversity Project which The Isles of Scilly Wildlife Trust has been running for the last two years to find out more about the special marine life of Scilly, and to raise awareness among visitors and locals alike about the importance of the area for marine species. The project is funded by Natural England�s Countdown 2010 fund and The Crown Estate, and this expedition was further helped by the generosity of Isles of Scilly Travel who have been supportive of the project from the start.
Isles of Scilly Travel are also giving Scillonian III passengers the chance to spot various marine species on their Wildlife Watching trips, including; porpoises, minke whales, basking sharks and sunfish, as well as a good selection of seabirds. Trips are guided by Paul Semmens who works with both The Isles of Scilly and Cornwall Wildlife Trusts. The final Wildlife Watching trip of the season will be on Saturday 16th October. Please call 0845 710 5555 and quote Wildlife Trust to qualify for the discounted price of �25 return or download the voucher from www.cornwallwildlifetrust.org.uk/whatson.
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