1 / 36

SLECI Direct observations by divers in sublittoral communities

SLECI Direct observations by divers in sublittoral communities. B.E. Picton Zoology Department, Ulster Museum, Belfast. Overview. Baseline - Erwin et al ., Ulster Museum Methodology Position fixing issues Range of sublittoral communities Communities assessed

walker
Download Presentation

SLECI Direct observations by divers in sublittoral communities

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SLECI Direct observations by divers in sublittoral communities B.E. Picton Zoology Department, Ulster Museum, Belfast

  2. Overview • Baseline - Erwin et al., Ulster Museum • Methodology • Position fixing issues • Range of sublittoral communities • Communities assessed • Extent and distribution within lough • Changes observed and possible causes

  3. Ulster Museum 1973-1980 • 1973, 1975, 1976, 1977 • Position fixing by Horizontal Sextant Angles • Continuous transects to determine boundaries between communities • Animals only • 1978 BBC film ‘Down under Down’ • 1980 detailed species surveys

  4. Northern Ireland Sublittoral Survey 1982-85 • Points at 2.5m, 7.5m, 15m, 25m, 35m on transects • Decca positioning, corrected to charts • Photography and observations • Whole of NI coastline • Plants and animals • Published 1990 as Inshore Marine life of Northern Ireland • Recommendations for Marine Reserves

  5. National Trust 1988-89 • Bob Brown et al. • Response to unprecedented trawling activity for Queen scallops • Area being fished for Queens • Photography and observations • 100m point transects • Video filming

  6. SLECI 2003 methodology • Revisit range of communities in main body of Lough • Pairs of divers scoring abundance using SACFOR scales • Marine Nature Conservation Review (MNCR – JNCC) methodology • Video transects • 100m line transects marked at 1m intervals • Quadrat samples at chosen sites

  7. Position fixing issues • Historical positions apparently too far east when revisited • Strangford chart georeferenced in ARCGIS to WGS84 • Historical data corrected to WGS84 • SLECI positions from GPS using WGS84 • All data compared using ARCGIS • East-West discrepancy approx 75m

  8. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix

  9. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix • Muddy sand with Amphiura filiformis

  10. Muddy sand with Amphiura filiformis

  11. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix • Muddy sand with Amphiura filiformis • Sandy mud with Amphiura chiajei

  12. Sandy mud with Amphiura chiajei

  13. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix • Muddy sand with Amphiura filiformis • Sandy mud with Amphiura chiajei • Mud with Nephrops norvegicus

  14. Mud with Nephrops norvegicus

  15. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix • Muddy sand with Amphiura filiformis • Sandy mud with Amphiura chiajei • Mud with Nephrops norvegicus • Modiolus beds with hydroids

  16. Modiolus beds 1973 - 1985 Modiolus beds Sparse Modiolus Modiolus with hydroids community

  17. Range of sublittoral communities • Boulders and gravel with brittle stars Ophiocomina/Ophiothrix • Muddy sand with Amphiura filiformis • Sandy mud with Amphiura chiajei • Mud with Nephrops norvegicus • Modiolus beds with hydroids • Modiolus/Chlamys beds

  18. Modiolus beds 1973 - 1985 Modiolus beds Sparse Modiolus Modiolus/Chlamys community Main channel 85% Green Island channel 10% Jane’s Rock channel 4%

  19. Long Sheelah - August 1988 Modiolus modiolus Iophon hyndmani on Chlamys varia Spanioplon armaturum on Chlamys varia Mycale cf. contareni on Aequipecten opercularis

  20. E of Drummond Is. - August 1988 Iophon hyndmani on Chlamys varia Spanioplon armaturum on Chlamys varia Munida rugosa

  21. E of Drummond Is. - August 1988 Iophon hyndmani on Chlamys varia Macropodia rostrata

  22. Modiolus beds 1977

  23. Queen scallop fishery 1987-89 Modiolus beds Sparse Modiolus • 1987 sudden increase in fishing for queenies • National Trust asks for fishing to be stopped • 1990 ROV survey shows extensive damage to Modiolus

  24. Fisheries legislation 1993 1993 Trawl Zone • Trawl zone covers most of Modiolus beds • Legitimises fishing in critical area • Introduced with agreement of EHS • Monitoring for recovery of beds promised

  25. Modiolus beds 2003 Modiolus beds Sparse Modiolus Mud with shells • Modiolus/Chlamys almost extinct • Black rock beds heavily silted • New area discovered west of Round Island Black Rock New area

  26. North of Long Sheelah

  27. Intact Modiolus/Chlamyscommunity - 2003

  28. Trawl zone

  29. Trawl zone - 2003

  30. Species increasing • Mycale similaris • Balanus crenatus • Liocarcinus corrugatus • Mytilus edulis • Pecten maximus • Ostrea edulis • Antedon bifida • Thyone roscovita

  31. Species decreasing • Spanioplon armaturum • Iophon hyndmani • Protula tubularia • Modiolus modiolus • Aequipecten opercularis • Chlamys varia • Munida rugosa • Thyonidium drummondi • Pyura microcosmus • Corella parallelogramma

  32. Notable species unchanged • Virgularia mirabilis • Sagartiogeton laceratus • Doto cuspidata • Aeolidiella glauca • Arctica islandica • Eucratea loricata • Leptasterias mulleri • Boltenia echinata

  33. Possible reasons for change • Global warming • Decreasing species all from Modiolus community • No clear change in northern/southern species ratio • Disturbance • Trawl zone shows most change • K-selected species decreasing, r-selected increasing • Increased sedimentation • Sponges reduced in abundance and diversity • Modiolus buried in mud

  34. Effects of sedimentation • Sponges sensitive to sedimentation • Sponges protect scallops from predators, especially starfish • Modiolus beds trap and sequester sediment • Removal of Modiolus beds releases sediment into water column

  35. Conclusions • Species and communities in Strangford Lough mostly unchanged in distribution and abundance • Modiolus beds are easily damaged by trawling and do not recover easily • Modiolus beds continue to decline even under moderate fishing or disturbance • Activities which cause resuspension of sediment should be avoided • Monitoring within Strangford Lough has been inadequate • Natural fluctuations in most marine invertebrate populations are poorly understood

  36. Acknowledgements • Carys Davies - analysis • Tim Mackie – additional video, boat • Divers – Carys, Tim, Dave Smyth • Assistant divers - Sam Vize, Annika Mitchell, Joe Breen, Dave Vincent, Rachel Oates, Christine Picton, Mark Armstrong, James Strong

More Related