The Isles of Scilly Biodiversity Audit 2008 - Cornwall Wildlife Trust

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2.2.1.11 Crustacea – Crabs, lobsters,shrimps and relativesOverviewThe crustaceans are a group of animals with jointedlegs and chitinous exoskeletons which are shedperiodically. The largest order is the Decapoda whichincludes shrimps, crabs and lobsters. There are over2000 species of crustacean in the waters surroundingthe British Isles, many are planktonic. Mostcrustaceans are mobile but some, like the barnacles,adopt a sessile lifestyle in their adult form.Crabs and shrimps are very common in intertidalareas. Shrimps are targeted by an artisanal fishery atspring low tides during the summer months in Scilly.Some crab species, lobsters and crayfish are caught bypotting in the fishing season. There is a high diversityof isopods in Scilly; they are common under algae andin fresh water seeps on the shore (Parslow, 2007).Important AreasCrustaceans are found in a wide range of habitatssuch as intertidal pools, under boulders and in softsediment. One species, the chameleon prawn Praunusflexuosus, is found in vast numbers in Bryher Pool, abrackish environment, but most are marine (Parslow,2007).Conservation ImportanceCthalamus barnacles dominate the rocky shores inScilly, unlike on mainland Southwest coasts whereSemibalanus balanoides is often dominant. This isthought to be due to larval supply problems for S.balanoides, which is rare in Scilly (English NatureNatural Area Profile).A rare hermit crab Cestopagarus timidus has beenrecorded in intertidal areas in Scilly (Harvey, 1964),this is a species which typically has a more southerlydistribution. There are also two recent records of rareslipper lobsters Scyllarus arctus another species at thenorthern limit of its range around Scilly (Herdson,2001). One individual was caught in a lobster pot andis now in the National Marine Aquarium in Plymouth.Typton spongicola, the sponge shrimp is a nationallyrare southern species which occurs in the Isles of Scillyon sponges. Cranch’s spider crab Achaeus cranchii isfound on subtidal hydroids, bryozoans and seasquirts(Barne et al, 1996).Several nationally rare or scarce amphipods have beenrecorded in Scilly. Microdeutopus stationis, Ampherusaclevei and Pereionotus testudo are nationally rare (NBN)and Apherusa ovalipes is nationally scarce (Barne et al,1996). Synisoma lancifer a nationally scarce sea slater isalso found in the Isles of Scilly.Trends and IssuesResearchInventories of some crustacean groups have beenpublished in the Journal of Natural History. These arethe Eucarida (Thurston, 1969), Harpacticoid copepods(Wells, 1970), Ostracods (Neale, 1970) and Mysidshrimps (Makings, 1987).Release of captive bred lobstersThe National Lobster Hatchery at Padstow has workedwith members of the Isles of Scilly Sea FisheriesCommittee and local divers to release 500 juvenilelobsters in 2002 and 120 in 2007 in the Isles of Scilly.These were released by hand in suitable habitats andwill take many years to grow large enough to enter thefishery.FishingPotting for lobsters, crayfish and crabs has occurred inScilly for many years. The impact on local populationsis largely unquantified. See section 3.3 on Fisheries.Spiny spider crab Maja squinado on dead man’s fingers Alcyonium digitatum. Photo: Frank GloysteinIsles of Scilly biodiversity audit Page 24
2.2.1.12 Myriapoda - Centipedes andMillipedesOverviewCentipedes and millipedes belong to the classMyriapoda characterised by the number of legs theypossess. Centipedes are carnivores and millipedes eatvegetation, both are important members of the groundflora community, assisting in the breakdown of leaflitter and processing of organic matter.They live in a variety of terrestrial habitats in the Islesof Scilly.Conservation ImportanceThere is one species on the BAP priority list:Turk’s Earth-centipede Nothogeophilus turkiThis species was collected by Dr F.A. Turk andidentified as a new species as recently as 1988.Trends and IssuesResearchThe distribution and population of Nothogeophilus turkishould be established.Important AreasThe type locality for Nothogeophilus turki is Old TownBay, St Mary’s.White-legged snake millipede Tachypodoiulus niger on an apple. Photo: Colin ButlerIsles of Scilly biodiversity audit Page 25
Page 1 and 2: The Isles of ScillyBiodiversity Aud
Page 3 and 4: ContentsForeword Page 5Acknowledgem
Page 5 and 6: ISLES OF SCILLY BIODIVERSITYForewor
Page 7 and 8: ExecutiveSummary1 IntroductionObjec
Page 9 and 10: 1Introduction1.1 Objectives of Isle
Page 11 and 12: 2Isles of ScillyBiodiversityThe bio
Page 13 and 14: 2.2.1.1 Marine algae - seaweedsOver
Page 15 and 16: 2.2.1.2 Charophytes - StonewortsOve
Page 17 and 18: 2.2.1.5 Bryophytes - Mosses andLive
Page 19 and 20: 2.2.1.7 Porifera - spongesOverviewS
Page 21 and 22: die-off occurred. The timid burrowi
Page 23: 2.2.1.10 Arachnida - Spiders andrel
Page 27 and 28: 2.2.1.14 Orthoptera - Crickets,Gras
Page 29 and 30: 2.2.1.16 Lepidoptera - Butterflies
Page 31 and 32: 2.2.1.18 Hymenoptera - Wasps andBee
Page 33 and 34: 2.2.1.20 Coleoptera - BeetlesOvervi
Page 35 and 36: 2.2.1.22 Mollusca - Slugs, snails,b
Page 37 and 38: 2.2.1.24 Echinoderms - sea urchins,
Page 39 and 40: 2.2.1.26 Lesser-studied phylaOvervi
Page 41 and 42: 2.2.1.27 Amphibia - frogs, toads an
Page 43 and 44: with herring Clupea harengus and ma
Page 45 and 46: 2.2.1.29 Terrestrial ReptiliaOvervi
Page 47 and 48: 2.2.1.31 BirdsOverviewSeabirdsThe I
Page 49 and 50: 2.2.1.32 Terrestrial MammalsOvervie
Page 51 and 52: commonest species of dolphin in the
Page 53 and 54: Habitat Areas -An IntroductionSt Ma
Page 55 and 56: 2.2.2.1 Arable Field MarginsOvervie
Page 57 and 58: 2.2.2.3 Coastal Vegetated ShingleOv
Page 59 and 60: Rocky reef with jewel anemones Cory
Page 61 and 62: 2.2.2.6 Intertidal BouldersOverview
Page 63 and 64: 2.2.2.8 Lowland HeathlandOverviewLo
Page 65 and 66: 2.2.2.10 Marine Sands and GravelsOv
Page 67 and 68: 2.2.2.11 Maritime Cliff and SlopesO
Page 69 and 70: 2.2.2.13 ReedbedsOverviewReedbeds a
Page 71 and 72: 2.2.2.15 Seagrass BedsOverviewSeagr
Page 73 and 74: 2.2.2.16 Standing Open Water(Eutrop
Page 75 and 76:
2.2.2.18 Wet WoodlandOverviewThis h
Page 77 and 78:
3.1 Nature ConservationOverviewPubl
Page 79 and 80:
3.2 AgricultureOverviewAlthough tou
Page 81 and 82:
3.3 FisheriesOverviewFor many years
Page 83 and 84:
3.4 Built DevelopmentOverviewAs wit
Page 85 and 86:
3.6 Air & Terrestrial PollutionOver
Page 87 and 88:
chemical dispersants will only be u
Page 89 and 90:
3.9 Climate Change / Sea LevelRiseO
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3.11 Economic DevelopmentOverviewTh
Page 93 and 94:
4Priorities for BiodiversityConserv
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Gracilaria bursa-pastoris A red sea
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Eriopus apiculatus A moss RDB Shade
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Spergularia bocconei Greek Spurrey
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Lucernariopsiscampanulata A stalked
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Agrochola lychnidis Beaded Chestnut
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Aphrosylus mitis A fly NS Uncommon
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RecommendationRecommendationRecomme
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Prionace glauca Blue Shark BAP Comm
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22Cygnus columbianusbewickiiTundra
Page 113 and 114:
RecommendationMARINE MAMMALSSpecies
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5Recommendationsfor ActionThe role
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Glossary6Alluvial sediment - partic
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Bibliography7Aprahamian M and Robso
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Harris T (1972) The Marine Flora an
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Scilly, Journal of Conchology 4, 28
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The Isles of Scilly Biodiversity Audit 2008 - Cornwall Wildlife Trust

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