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Sponge Reefs M. Krautter, U. Stuttgart Sponge Reef Project, 1999 http://www.porifera.org/a/cif1.htm

Sponge Reefs M. Krautter, U. Stuttgart Sponge Reef Project, 1999

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Text of Sponge Reefs M. Krautter, U. Stuttgart Sponge Reef Project, 1999

  • Sponge ReefsM. Krautter, U. Stuttgart Sponge Reef Project, 1999 http://www.porifera.org/a/cif1.htm

  • Fig 4-8Sponge reefs occur on the continental shelfof the North Pacific

  • bioherms70 m highhttp://www.brookes.ac.uk/geologyReefs: Carbonate bodies Contain fossil organisms Biologically influenced Rigid framework

    Some are buried by sediment Others have positive reliefBioherms mounds (lens shaped)Biostromes flat (laterally extensive)

  • Ancient sponge reefs

  • J. Ghiold, New Scientist 1991Sponge reefs during the JurassicLocation of Jurassic reefs relative to modern Europe

  • Distribution of the main reef forming glass sponges

  • Glass sponges:Deep water animals (> 500 m usually)Skeleton of glass SiO2Soft tissue is largely multinucleate (syncytial)Can send electrical signals (like nerves)These signals shut down the feeding currentRespond to mechanical stimuli including sedimentTwo principal types: fused skeleton; loose skeleton

  • Glass sponges have a skeleton of silica dioxide (SiO2) = nearly pure glass

    In reef-forming glass sponges this is fused into a rigid scaffold as shown at right

  • The tissue of glass sponges is largely a multinucleate giant cell.

    The top image shows tissue growing in a petri dish

    The bottom image shows masses of nuclei (blue) scattered around massive microtubules (red) the length and straightness of the microtubules confirms that the sponge is syncytial.

  • The sponges live in a very turbid environment and can filter lots of sediment

  • Glass Sponges respond to sediment in their incurrent water by shutting down their feeding current

  • What have we learned about the reefs?

  • Core Formed on boulders at the edge of ice berg scours 8-10,000 years ago Northern reefs are 5-21 m thick Individual sponges are 50-220 years oldWhat have we learned about the reefs?

  • Glass sponges are affected by their environment. It is thought that the following conditions are required for growth of a sponge reef:Low temperature (7-12 oC)Low lightHigh dissolved silica (>50 uM)Low sediment juveniles need firm substrates to attach to.

  • Trawl marks have been found through one reefConservation

  • Summary:

    Glass sponges are abundant in deep water world wide but can be found in shallow water in 4 locationsOne type of glass sponge has a fused skeleton. These sponges form reefs by juveniles settling on the skeletons of adults. Reefs = bioherms.Sponge reefs were common during the Jurassic, when they formed a vast band across an area that is now much of Europe. These leave a fossil trace that can be found in rocky outcrops in Spain, France and Germany.Today living sponge reefs are only found in Canadian Pacific continental shelf waters (