Stable Tropics not so Stable: Climatically Driven Extinctions of Reef-Associated Molluscan Assemblages (Red Sea and Western Indian Ocean; Last Interglaciation to Present)

  1. G. F. Camoin2 and
  2. P. J. Davies3
  1. M. Taviani

Published Online: 27 MAY 2009

DOI: 10.1002/9781444304879.ch4

Reefs and Carbonate Platforms in the Pacific and Indian Oceans

Reefs and Carbonate Platforms in the Pacific and Indian Oceans

How to Cite

Taviani, M. (2009) Stable Tropics not so Stable: Climatically Driven Extinctions of Reef-Associated Molluscan Assemblages (Red Sea and Western Indian Ocean; Last Interglaciation to Present), in Reefs and Carbonate Platforms in the Pacific and Indian Oceans (eds G. F. Camoin and P. J. Davies), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304879.ch4

Editor Information

  1. 2

    CEREGE, Aix-en-Provence, France

  2. 3

    University of Sydney, Australia

Author Information

  1. Instituto di Geologia Marina del CNR, via Gobetti 101, 40129 Bologna, Italy

Publication History

  1. Published Online: 27 MAY 2009
  2. Published Print: 23 MAR 1998

ISBN Information

Print ISBN: 9780632047789

Online ISBN: 9781444304879

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Keywords:

  • depauperation of coral reef biota and local extinctions;
  • Red Sea marine biota extinctions in last glacial age;
  • micropalaeontological and isotopic data from offshore Red Sea;
  • Sea-level changes controlling coral reef growth;
  • tropical speciation by sea-level habitat-area fragmentation

Summary

The Indo-West Pacific coral reefs have experienced dramatic faunal turnovers since the last interglacial period, as documented by local extinctions and contractions of associated faunas in the western Indian and Pacific oceans. Although refrigeration of sectors of the Indo-Pacific region is a possible concomitant limiting factor, rate of sea-level change is considered the most important constraint in controlling the ultimate fate of Quaternary coral reefs. Disruption of internal organization at times of rapid sea-level fluctuations may lead to progressive depauperation of coral reef biota through local extinctions. In the case of the shallow-silled Red Sea basin, effects of sea-level changes were dramatically amplified and the entire basin underwent massive destruction of its stenoecious biota as a result of the onset of high-salinity conditions. Similar disturbances punctuated the entire Quaternary ice age, possibly causing many, high-frequency faunal rearrangements of variable intensity in coral reef ecosystems. Habitat fragmentation within the Indo-West Pacific region is seen as a major mechanism to account for the high level of species-level biodiversity witnessed throughout the Cainozoic. Speciation is apparently promoted through gene-flow disruption among populations within the Indo-West Pacific during times of relative lowstands. Endemics seem to be preserved rather than lost, when populations reconnect at the re-establishment of highstand conditions. Thus, the Indo-West Pacific tropical region acts as a vast refuge at peaks of glacial difficulties. However, this is not the general rule for the tropics, as indicated by a decrease in coral diversity in the Caribbean. During the last glaciation, the capacity of the Red Sea and Persian Gulf to sequester CO2 through calcification in both the pelagic and neritic domains practically reached zero. This fact, and the concomitant reduction of coral reefs in other areas of the Indo-Pacific region, should be taken into account in the evaluation of the global CO2 cycle.