SettlementPlates

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Newly Installed Settlement Plates [1]

Settlement Plates

What are settlement plates?

Settlements plates are man-made devices that simulate the natural strata that corals settle on. Corals settle on the plates during a given time period, and the plates are removed and analyzed in a lab. The amount of coral larvae (coral spat) on each settlement plate allows scientists to learn about the recruitment and, therefore, the health of the reef. Also, scientists often use settlement plates to determine the timing of coral spawning events.


Obviously, settlement plates are found in coral reefs or places where corals are able to live. The orientation and position of settlement plates on the reef are very important. Flow and coral abundance varies greatly throughout the reef. It would not be accurate to compare a vertically oriented settlement plate at 10 meters deep to a horizontal settlement plate at 5 meters deep.


Different types of settlement plates include ceramic tiles, petri dishes, glass, dead branching coral, and slices of stony coral. Ceramic tiles are the best option because they are inexpensive, easy to replicate, easy to analyze in a lab, and are similar to the calcium carbonate strata that corals naturally settle on.

What do settlement plates measure?

  • Coral recruitment [2]
    • Health of coral reef
    • Scientists don’t know much about the coral reproduction process
Brain Coral budding [3]
    • Phi Phi Islands case study (recruitment after tsunami) [4]

How are settlement plates used?

  • Methods and different types of Settlement plates [5]
    • Similar Depth
    • Similar attachment mechanisms
      • Wire mesh
      • Steel bolts
    • Place the settlement plates before a known spawning period or leave them there for a complete season cycle
    • Label, bleach, dry
    • Examine with a dissection microscope
  • Why use Settlement Plates [2]
    • Able to be removed from reef
    • Yields comparable data to natural reef substrata without damaging the reef

Problems with Settlement Plates [5]

  • Typically use surfaces not found in the natural environment
  • Difficult to know where in the reef to place them. Drastic difference between plates only 5 meters apart
  • Vertical and horizontal surfaces produce different results
  • Expensive based on type of settlement plate
  • Cannot directly compare different settlement plates
    • Some have horizontal and vertical dimensions
    • Difficult to manipulate under a microscope
  • Destructive
    • Using live coral as a recruitment measure

Examples of settlement plates being implemented

  • St. John case study [6]
  • Phi Phi Islands, Thailand [4]
  • Australia, Great Barrier Reef near Cairns [7]



Notes

  1. "Eco Koh Tao | Eco Diving Courses, Gap Year Opportunities and Eco Internships - Koh Tao, Thailand." Eco Koh Tao | Eco Diving Courses, Gap Year Opportunities and Eco Internships - Koh Tao, Thailand. N.p., n.d. Web. 26 Feb. 2013.
  2. 2.0 2.1 Salinas-de-Leon, Pelayo, et al. "Scleractinian Settlement Patterns to Natural Cleared Reef Substrata and Artificial Settlement Panels on an Indonesian Coral Reef." Estuarine, Coastal and Shelf Science 93.1 (2011): 80-5. GeoRef. Web. 25 Feb. 2013.
  3. "Coral Reproduction." NOAA's Coral Reef Conservation Program:. N.p., n.d. Web. 28 Feb. 2013.
  4. 4.0 4.1 Phongsuwan, N., C. Richter, and Y. Sawall. "Coral recruitment and recovery after the 2004 Tsunami around the Phi Phi Islands (Krabi Province) and Phuket, Andaman Sea, Thailand." Helgoland Marine Research 64.4 (2010): 357+. Academic OneFile. Web. 25 Feb. 2013.
  5. 5.0 5.1 Harriott, Vicki J., and David A. Fisk. "A comparison of settlement plate types for experiments on the recruitment of scleractinian corals." Marine Ecology Progress Series. 37. (1987): 201-208. Print.
  6. Green, Daniel H., Edmunds, Peter J.. "Spatio-temporal variability of coral recruitment on shallow reefs in St. John, US Virgin Islands." Journal of Experimental Marine Biology and Ecology, Volume 397, Issue 2, 15 February 2011, Pages 220-229
  7. Harriott, V. J., and D. A. Fisk. "Recruitment Patterns of Scleractinian Corals: A Study of Three Reefs." AUST.J.MAR.FRESHWAT.RES. 39.4 (1988): 409-16. Environmental Sciences and Pollution Management. Web. 25 Feb. 2013.
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