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Downloaded by [Weizmann Institute of Science] at 03:22 26 June 2013 Chemistry and Ecology
Vol. 27, No. 2, April 2011, 121–127

Vermetid reefs in the Mediterranean Sea as archives of sea-level
and surface temperature changes

Renato Chemelloa* and Sergio Silenzib,c

aDipartimento di Ecologia, Università di Palermo, Palermo, Italy; bISPRA – Istituto Superiore
per la Protezione e la Ricerca Ambientale, Rome, Italy; cDipartimento di Scienze della
Terra, Università di Roma La Sapienza, Rome, Italy

(Received 14 July 2010; final version received 10 January 2011 )

Vermetid reefs are among the most important bioconstructions in the Mediterranean Sea, with a distribution
restricted to the warmest part of the basin. Their structure, and vertical and geographical distribution make
them good biological indicators of changes in sea level and sea-surface temperature over the last two
millennia.

Keywords: vermetid reef; sea-level change; sea-surface temperature; Mediterranean Sea

1. Introduction

In marine ecosystems, a bioconstruction is any structure built by living organisms that rises
from the bottom towards the surface and is able to modify the local environment both physically
and ecologically [1]. All bioconstructions increase in volume or thickness through progressive
stratification by generations of successive organisms. However, they can be eroded or destroyed
by other organisms and by physical factors, following a cycle of bioconstruction/bioerosion [2].

Whatever their origin, all bioconstructions share unique features, such as structural complexity
and rigidity. Structural complexity varies with building species, and depends on their growth
forms, the geology and morphology of the seabed, exposure and water depth. Structural rigid-
ity is due to the deposition of calcium carbonate in the form of skeletons or shells which,
by providing great resistance to breaking and eroding agents, also contribute to longer habi-
tat stability [3]. Furthermore, all bioconstructions have a positive topographic relief due to the
physiological response of the habitat builders to sedimentation, and the need for better nourish-
ment and favourable conditions for the associated symbionts. As a consequence, high growth
rates are needed to cope with marine erosion and borers (which account for the high produc-
tion of sediments associated with bioconstructions). In these systems, deposition and erosion are
opposite processes, the balance tilting toward deposition in growing buildups. This balance can
be influenced by the growth habit of the structure which can, at times, undergo a kind of ‘suicide’,
leading to its destruction by catastrophic events [4].

*Corresponding author. Email: chemello@unipa.it

ISSN 0275-7540 print/ISSN 1029-0370 online
© 2011 Taylor & Francis
DOI: 10.1080/02757540.2011.554405
http://www.informaworld.com