ANNALES • Ser. hist. nat. • 11 • 2001 • Suplement - Abstracts
Interdisciplinary Workshop "Pattern and Process in Balkan Biodiversity", Koper, September 25-28 2001
DIATOMS AS BIODIVERSITY INDICATORS IN LAKES OF THE CIRCUM-MEDITERRANEAN
Jane M. REED
Department of Geography, University of Hull, UK
Diatoms (single-celled siliceous algae) occur in virtually all water bodies, are abundant, diverse and sensitive to a 
wide range of water chemistry variables. In lake sediment studies of past environmental change, their power as 
highly sensitive monitors of temporal trends in environmental variables such as salinity (related to lake-level and 
climate change) or nutrient status is widely acknowledged. Over the past decade diatom research has advanced 
considerably, with the development of transfer functions based on large modern regional data-sets of water chemis­
try and diatom assemblage composition data, from which to quantify past changes in water chemistry variables.
The Mediterranean regions of the Balkans, Turkey and Spain contain a wide variety of wetlands, including fresh 
(hydrologically open) and saline (hydrologically closed) lakes. Many of these wetlands are threatened increasingly 
by the effects of human-induced eutrophication and accelerated water abstraction, such that issues surrounding con­
servation and biodiversity are of particular concern. Whilst existing diatom-based research has been aimed primarily 
at reconstructing past environmental change, the recent expansion of diatom study in these regions has produced for 
the first time large regional data-sets of modern ecological data and an increasingly large body of long (last c. IQ-
20,000 yr.) and short (last c. 150 yr.) term palaeolimnological data, from which to assess temporal trends in biodi­
versity, both on a site-specific and regional basis.
This paper explores the potential of diatoms as indicators of biodiversity in the circum-Mediterranean, based on 
modern ecological and palaeoecological studies of lakes of the Balkans, Turkey and Spain, and by comparison with 
previously published species inventories for particular lakes. The influence of taxonomic nomenclature, habitat 
variation and sampling site on apparent biodiversity is discussed, and temporal trends are assessed using simple 
biodiversity indices. It is suggested that one of the most valuable outcomes of using the long-term palaeolimnologi­
cal record to assess biodiversity, by reference to large modern ecological data-sets, is that one may identify clearly 
the past existence of characteristic diatom assemblages (and by inference, lacustrine environments) which now have 
no modern analogue in the regional flora.
Key words: diatoms, Mediterranean, palaeolimnology, biodiversity, transfer functions
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