Microatoll

In intertidal reef-flat environments, massive Porites form characteristic microatoll formations, with living coral around the perimeter and dead skeleton on the exposed upper surface.[1]

A microatoll is a circular colony of coral, dead on the top but living around the perimeter. Growth is mainly lateral, as upward growth is limited by exposure to air. Microatolls may be up to 6 meters (20 ft) in diameter.[2] They are named for their resemblance to island atolls formed during the subsidence of volcanic islands, as originally suggested by Darwin (1842).[3]

They act as natural recorders of sea level, which allows the monitoring of sea level changes in response to global warming. They have also been used to quantify and date changes in relative sea level in seismically active areas,[4] and to provide information on changes in sea surface temperature using oxygen isotope values as a proxy.[5]

  1. ^ van Woesik, R., Golbuu, Y. and Roff, G. (2015) "Keep up or drown: adjustment of western Pacific coral reefs to sea level rise in the 21st century". Royal Society, open science, 2 (7): 150181. doi:10.1098/rsos.150181
  2. ^ Stoddart, D.R.; Scoffin T.P. (1979). "Microatolls: review of form, origin and terminology" (PDF). Atoll Research Bulletin. 224: 1–17. doi:10.5479/si.00775630.224.1.
  3. ^ Darwin, Charles (1842). The structure and distribution of coral reefs. London: Smith, Elder and Co. p. 214.
  4. ^ Natawidjaja, D. H.; Sieh K.; Chlieh M.; Galetzka J.; Suwargadi B.W.; Cheng H.; Edwards R.L.; Avouac J.-P.; Ward S. N. (2006). "Source parameters of the great Sumatran megathrust earthquakes of 1797 and 1833 inferred from coral microatolls" (PDF). Journal of Geophysical Research. 111 (B06403): n/a. Bibcode:2006JGRB..111.6403N. doi:10.1029/2005JB004025. hdl:10220/8480.
  5. ^ Cite error: The named reference Goudie was invoked but never defined (see the help page).