The table to the right shows how many Phylum Common Name Number Common Species species were recorded in each group of species and some of the most widely Porifera Sponges 26 Shredded carrot sponge Esperiopsis fucorum distributed species. Boring sponge Cliona celata Anemones, corals, 30 Oaten pipe hydroid indivisa Sponges hydroids, jellyfish Dead men's fingers Alcyonium digitatum A wide diversity of sponges was Red fingers Alcyonium glomeratum recorded. Particularly common on Dahlia anemone Urticina felina exposed, westerly facing, sites was Elegant anemone Sagartia elegans Jewel anemone Corynactis viridis the carrot sponge Esperiopsis Devonshire cup coral Caryophyllia smithii fucorum (photo on inside page), which Platyhelminthes Flatworms 1 was much less common at the easterly Annelida Segmented worms 10 sites visited in September 2004. The Crustacea Crabs, lobsters, barnacles 14 Edible crab Cancer pagurus greatest diversity was on slightly silted Velvet swimming crab Necora puber ledges at Mussel Rock (16spp) and Mollusca Shells, sea slugs, cuttlefish 25 Coryphella browni Westward Ledges (15spp). The Bryozoa Sea mats 10 Sea Mat Membranipora membranacea Potato crisp bryozoan Pentapora foliacea nationally scarce Axinella damicornis Echinodermata Starfish, sea urchins, 11 Common starfish Asterias rubens was recorded from four different sites. sea cucumbers Spiny starfish Marthasterias glacialis Common urchin Echinus esculentus Anemones, Corals, Hydroids & Sea cucumber Pawsonia saxicola Jellyfish Tunicata Sea squirts 14 colonial sea squirt Aplidium punctum This is the most widely recorded of the Pisces Fishes 11 Ballan wrasse Labrus bergylta groups with 30 species, many Two spot goby Gobiusculus flavescens of which were very common. Mammalia Mammals (seals & dolphins) 1 Plumose, jewel and elegant Algae Seaweeds 35 Red rags Dilsea carnosa Sea beech Delessaria sanguinea anemones dominated many of CWthe branched brown seaweed Dictyota dichotoma vertical surfaces whilst Devonshire Cuvie Laminaria hyperborea cup-corals and dahlia anemones were Furbelows Saccorhiza polyschides found in areas with some sediment. Angiospermae Flowering plants 1 Eelgrass Zostera marina Three nationally scarce species were Total Species 147 Isles of Scilly Survey recorded, including pink sea fans, but none were common. Molluscs Bryozoans The oaten pipe hydroid, Tubularia The 25 species recorded included 14 There were a number of prominent species, May 2005 indivisa and the smaller Tubularia different nudibranchs (sea slugs). including the potato crisp bryozoan, Pentapora larynx (below), were prominent at They were commonly found feeding, foliacea, which is a typical clear water species. Summary Report many sites. These species are usually especially on the hydroids. They Fi shes abundant in suitable locations in the included the sponge nudibranch, The most common fishes in the study area were Peninnis Head, St Mary’s MF spring and are an important food Doris sticta (below), which is wrasses with all five British species recorded. source for many sea slugs, whose nationally scarce. The ballan wrasse was the most common. numbers also peak at this time. Seaweeds and Seagrasses In situ identification of seaweeds is a specialist task and at most sites only the most prominent species were recorded. The sea beech, Delessaria sanguinea (right) was especially common. A large healthy eelgrass bed was MF recorded in the Tresco Channel. CW Starfish, Sea urchins Nationally scarce and Biodiversity Action Plan species CW and Sea cucumbers Whilst the diversity of Species Designation Where found Crabs and Lobsters Sponge echinoderms was low, the These were not common at any of the Axinella damicornis scarce Occasional - 4 sites s p i n y s t a r f i s h , Pink sea fan sites though commerical species such peacock worm MF jewel and plumose anemones CW Marthasterias glacialis, Eunicella verrucosa scarce/BAP 6 sites - common at 1 but rare as the edible crab and lobster were common sea urchin, elsewhere both regularly recorded in small Yellow cluster anemone Echinus esculentus, and numbers. Most surprising was the lack Parazoanthus axinellae scarce Men-a-vaur only, rare cottonspinner, Holothuria Scarlet and gold star coral of spiny spider crabs, which were only forskali were commonly Balanophyllia regia scarce Peninnis Head only, frequent seen at two sites and were recorded recorded. These are all Sponge nudibranch as rare on those occasions. This is a Doris sticta scarce Rare - 4 sites typical south-westerly widespread and common species Eelgrass species. Zostera marina BAP Tresco Channel elsewhere in SW Britain. Nationally rare and scare as defined by JNCC.

This Seasearch survey was organised as a part of the Marine Conservation Society’s Member’s Dives Seasearch is a volunteer underwater survey project for Programme. Surveyors taking part were: recreational divers to contribute to the conservation of the Vicki Billings, Fiona Crouch, Mike Flavell, marine environment. Financial support for the project during Christine Harling, Rohan Holt, Chris Pirie, 2005/6 and for the production of this summary report has been Kirsten Ramsay and Chris Wood. Other given by: divers were Sam Cook, Pete Lilley, Darren Murray and David Vinicombe. We would also like to thank Jolene and Tim Allsop. spiny starfish and elegant anemones CW Coryphella browni MF Text by Chris Wood. Photographs by Mike Flavell (MF), and Chris Wood (CW). Great High Rock 10 Tresco Channel 12 The channel between Tresco and Maen-a-vaur 8 & 11 The gully is open to the north and This is a coastal site on Bryher comprises sand and gravel narrows and shallows to the the west side of Bryher. Two contrasting sites were with mixed brown, red and green south. There was kelp forest on The main physical visited, the narrowing gully seaweeds, including very large the upper parts with sparse kelps feature is a surge gully between the two parts of the sugar kelps, L. saccharina. and a mixed algal/animal turf with rock sides and rock and walls and pinnacles On the eastern side of the channel below. boulders in the bottom, to the west of the main rock. is a dense and healthy eel grass At the southern end there were leading to a boulder The steep sided rocks on the bed with many snakelocks typical surge gully conditions with slope. There was kelp westerly site had species a n e m o n e s , r e d - s p e c k e d scoured bedrock, pink encrusting cover in the shallows such as the dead mens pimplets, Anthropleura ballii, and a l g a e a n d a c o m m u n i t y and a variety of sponges, fingers shown to the right. a variety of tube worms. dominated by Dendrodoa sea shore crabs mating MF e s p e c i a l l y c a r r o t 2 MF squirts, and Clathrina sponge. sponge. Esperiopsis 8 carrot sponge MF fucorum. 11 Trinity Rock 1 9 3 This is a rocky reef with Westward Ledge 7 & Mussel Rock 4 1 RH 9 the top at a depth of Both sites have exposed 16m and steep rocky vertical walls from shallow water 5 walls to 37m. The site 12 St Martins to at least 30m. In the case of 10 has a very irregular Mussel Rock there is then a Bryher t o p o g r a p h y w i t h slope of very large boulders and Tresco Cerinathus lloydii MF numerous drops offs CW bedrock slabs, whilst the wall at 7 Eastern Isles and pinnacles. It was The main kelp plant on the reef Westward Ledge went down to 5 n o t a b l e f o r t h e 50m. top was Laminaria ochroleuca 6 p r e s e n c e o f t h e (above) which is limited to The Westward Ledge wall was football sea squirt, south-west England. The dominated by oaten pipe Diazona violacea, At Mussel Rock (above), the more widely distributed L. hydroids, Tubularia indivisa, potato crisp bryozoans deep rocks had flat ledges with a Samson hyperborea was also present. which were being eaten by 1 and soft corals. nudibranchs, principally little silt and many cup corals and Coryphella browni. Elegant sponges. Sixteen species of Peninnis Head 2 St Marys 7 There was a good deal of sponge were recorded here. anemones were also common. This is a coastal site with angling debris close to the vertically sided deep gullies point. Wrecks of the Delaware 5 and Empire 6 directly off the point and large 8 boulders at the base. The Both of these sites consist of flat oaten pipe hydroid, Tubularia gullies were notable for the rocky seabed with small indivisa. presence of the nationally amounts of wreckage providing The site of the Empire also 9 6 2 scarce scarlet and gold cup some variety of topography. The had an algal turf but was coral. Balanophyllia regia notable for the abundance of Delaware site is slightly Annet seen left with a Devonshire shallower and had a red algal t h e c a r r o t s p o n g e , cup-coral Caryophllia smithii Esperiopsis fucorum St Agnes turf with sparse kelp on the . Eight on its right. MF shallower parts. The main piece different nudibanchs, sea of wreckage was covered in slugs, were recorded here. Lethegus Rocks - wrecks of Plympton & Hathor 3 3 This site was notable mainly for the rich tall In the same habitat were many 4 Trenemene Wall animal turf on the upturned hull of the wreck of potato crisp bryozoans, This is a classic Scillies wall the Plympton. This was the only location Pentapora foliacea, the with an abundance of Western Rocks throughout the week where significant numbers hedgehog sponge, Polymastia sites surveyed during this survey plumose, jewel and elegant of pink sea fans, Eunicella verrucosa, were b o l e t i f o r m i s a n d o t h e r sites surveyed in September 2004 anemones on a vertical face to 4 found (right). The wreck dates from 1909 and branching sponges. about 45m depth. Hydroids, the density of sea fans was up to one colony per Tubularia indivisa, were also Survey sites square metre. This appears to be an area were common at this time of year. The sites surveyed were limited by strong winds during the second half there is a variety of local current flows as there Atlantic grey seals are of the survey week, and at this time we were only able to dive sites to the were a number of colonies with branches in common on the Western north and west as the winds were from the east. However, this was the more than one plane. The condition of the sea Rocks and we were joined by a opposite of the conditions during the previous survey in 2004 and fans was good and, as at other sites in the seal in shallow water at the means that 21 different sites throughout the islands have been islands, there was a proportion of white colonies, end of our dive. CW surveyed within the last year. 31% in this case (5 out of 16 fans measured). MF