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Coral reef restoration by electrolysis

Coral reef restoration by electrolysis. From a lecture held February 18, 2008 by Susanna Strömberg for a course in Marine Conservation Biology, at Sven Lovén Centre for Marine Sciences, Tjärnö University of Göteborg Sweden. Photo: T. Lundälv. Coral reef restoration by electrolysis.

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Coral reef restoration by electrolysis

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  1. Coral reef restoration by electrolysis From a lecture held February 18, 2008 by Susanna Strömberg for a course in Marine Conservation Biology, at Sven Lovén Centre for Marine Sciences, Tjärnö University of Göteborg Sweden Photo: T. Lundälv

  2. Coral reef restoration by electrolysis • Coral occurrences in swedish waters • Why restoration is needed • The method – history and how it works Photo: T. Lundälv

  3. Global distribution Map from UNEP-WCMC Map: Roshani Sitaula, Bremen University

  4. Deep-water corals in swedish waters NORWAY S. Søster Fjellknausene Saekken Djupekrakk Tisler Strömstad • only one remaining coral reef in swedish waters • 5-6 known former reef sites • trawling is the main reson for extinction • The Saekken reef is protected against trawling since 2001 TMBL Living Extinct TMBL: Tjärnö Marine Biological Laboratory

  5. Prerequisites for corals • temp. 4°-13°C • salinity 32-38,8‰ • depth 39 m - 3 383 m • enhanced bottom currents • growth rate 4–25(19-34 on oil rigs)mm/year Multibeam map and photo: T. Lundälv • THREATS • trawling • oil and gas exploitation • acidification

  6. The Saekken reef is sensitive to disturbances • Small colonies • easily over-turned • Illegal trawling • tracks from trawling gear and disturbed colonies reported in 2004 • Low genetic variation • high clonality (70%) • reproduction mainly by fragmentation • Isolated from other reefs Photos: T. Lundälv

  7. Increased diversity close to corals Lopheliapertusa UV photos: T. Lundälv Panel photos: S. Strömberg

  8. Coral reefs important habitats • invertebrate abundances much higher close to corals • species richness higher • major taxa;Protozoa, Bryozoa, Cnidaria and Annelida (Polychaeta) S2 & S3 has been close to corals Results from a settling experiment at the Saekken reef site (2001-2007), unpublished data. (Susanna Strömberg)

  9. Electrodeposition in seawater- for restoration purposes Wolf • The method was developed by architect Wolf Hilbertz in the mid 70ies • Dr Thomas Goreau invited Wolf to Jamaica in the mid 80ies and tested the method for the purpose of restoring tropical reefs • Since then the method has been used in Indonesia, Maldives, Mexico, Panama, Papua New Guinea, Saya de Malha, Seychelles, Thailand and Palau Tom Photos fromwww.biorock.net

  10. Photo: W. Hilbertz, 2001 Photo: W. Hilbertz, 2002

  11. Pemuteran Bay, Bali, Indonesia Mach, 2006 Photo: Wolf Hilbertz

  12. Observed effects on tropical corals • 3-5 times faster growth rates • copes with stress better • more active polyps • enhanced settling of coral larva Photo: J. Cervino, Bali 2004

  13. magnesium hydroxide calcium carbonate Cathode - Photo: Wolf Hilbertz

  14. Mineral deposition through electrolysis 2H2O + 2e- H2 + 2OH- 2H2O  4H+ + O2 + 4e- (2Cl- Cl2 + 2e-) Ca 2+ + CO32- OH- + HCO3- + Ca2+ CaCO3 + H2O 2OH- + Mg2+ Mg(OH)2 0,1-30 ampere 0-12 voltage Deposition of minerals on the cathode e- Anode + (coated titanium) lowered pH, oxidation Cathode – (iron or steel) alkaline (~0,1 pH units) reduction

  15. 1,5 years of mineral deposition(2-2,5 cm) Photo from www.biorock.net

  16. Aragonite –coral skeleton & elektrodeposition Orthorombic structure CaCO3 Calcite – lime stone Tetragonal structure Illustrations from Wikipedia

  17. Ca2+ + 2HCO3-  H2O + CaCO3 + CO2 • The coral polyp excretes a calcium carbonate skeleton in the form of aragonite • Enzymatic transformation of carbon dioxide to carbonate ions that reacts with calcium cations and form calcium carbonate • Produces an alcaline environment within the calicoblastic cells to drive the production of calcium carbonate Illustration from Wikipedia

  18. Ca2+ + 2HCO3-  H2O + CaCO3 + CO2 • The coral polyp excretes a calcium carbonate skeleton in the form of aragonite • Enzymatic transformation of carbon dioxide to carbonate ions that reacts with calcium cations and form calcium carbonate • Produces an alcaline environment within the calicoblastic cells to drive the production of calcium carbonate Illustration from Wikipedia

  19. Ca2+ + 2HCO3-  H2O + CaCO3 + CO2 • The coral polyp excretes a calcium carbonate skeleton in the form of aragonite • Enzymatic transformation of carbon dioxide to carbonate ions that reacts with calcium cations and form calcium carbonate • Produces an alcaline environment within the calicoblastic cells to drive the production of calcium carbonate Illustration from Wikipedia

  20. increased atmospheric CO2 decreases [CO32-] due to increased[H+] CO2 higher temp – lower solubility lower temp – increased solubility H2O + CO2 H2CO3 HCO3- + H+ CO32- + H+ calcification dissolution [H+]/[OH-] Ca2+ + 2HCO3- H2O + CaCO3 + CO2 increased pH decreased pH saturation horizon for aragonite saturation horizon forcalcite

  21. Conclusions • Deep-water coral reefs are important habitats • Shallow reefs are damaged by trawling • Deeper reefs are threatened by ocean acidification There is a need for restoration efforts Eunice norvegica (Polychaeta) Alcyonium cf norvegicum (Octocorallia) Photos: S. Strömberg

  22. Thank you for your attention! Eunice norvegica Photo: S. Strömberg

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