RECONSTRUCTION OF SEAGRASS DYNAMICS - AGE-DETERMINATIONS AND ASSOCIATED TOOLS FOR THE SEAGRASS ECOLOGIST

All seagrasses are rhizomatous plants that grow by reiteration of a li mited set of modules. Their past growth history can therefore be recon structed from the scars left by abscised leaves and flowers on the lon g-lived rhizomes or the seasonal signals imprinted in the frequency an d size of their modules. We provide here the basic foundations and ass umptions of these reconstruction techniques and the calculations invol ved in their application. We then show their reliability and potential to quantify an array of ecological processes, such as plant demograph y, leaf and rhizome production, flowering intensity, and seagrass resp onses to anthropogenic perturbations, based on our recent studies of M editerranean, Caribbean and Indo-Pacific seagrass species. Reconstruct ion techniques have also proven useful in demonstrating the role of se agrasses as tracers of sediment movement over seagrass beds and the ra tes of colonisation and expansion of seagrass patches. These reconstru ction techniques should provide a powerful tool to improve our knowled ge of seagrass species and populations from remote areas based on a si ngle or just a few visits. This should, therefore, allow us to sample many seagrass meadows using limited resources, thus generating a stron g foundation for the study of comparative seagrass ecology and testing of theories previously applied to terrestrial plant populations.