8. Occurrence of benthic microbial mats in saline lakes

Abstract

Microbial mats, both fossil and living, have been of interest to micropalaeontologists, microbiologists and sedimentologists for at least the last 50 years (see Walter, 1976). Living mats from a variety of freshwater and marine environments, including hot springs, have been studied for reasons related to the biology and activities of component microorganisms and to their geological significance (e.g. Castenholz 1969; Gebelein 1969; Eggleston & Dean 1976; Brock 1978; Bauld, Chambers & Skyring 1979). Wetzel (1964) has pointed out that limnological investigations of saline lakes are disproportionately large in relation to their relative frequency of occurrence. Such has not been the case, however, for studies of microbial mats in saline lakes. Limnology developed primarily through examination of open-water planktonic systems and limnologists, as a group, still display a mystifying propensity for studies of the planktonic, faunal and chemical components of saline lake ecosystems. It is entirely possible that the relative lack of data about benthic mats is attributable not only to the putative scarcity of mats themselves, but also to the major interests of limnological investigators. To the best of my knowledge there has been no publication which presents an overview of the occurrence, composition and functional biology of salt lake microbial mats. As we shall see, the level of detail of the information available ranges from brief references in major studies of other elements of the salt lake habitat, e.g. Vareschi's work on flamingo feeding (Vareschi 1978), to intensive studies of mat components and dynamics, e.g. the series of papers on Solar Lake by Cohen and collaborators. The following is an attempt to bring together a coherent body of information concerning salt lake mats. This review, therefore, has the following limited objectives. Firstly, to assemble and collate for the first time in a single paper a substantial portion of the published, though widely scattered, literature which refers to or discusses microbial mats in salt lakes. Secondly, to lay the groundwork for a more detailed discussion (Bauld, in preparation) of the biological and geological activities and significance of these structures. Thirdly, to draw the attention and interest of limnologists to a largely ignored but potentially significant component of salt lake ecosystems. This review is not an exhaustive summation of the literature but it is sufficiently comprehensive to be of value to potential 'matologists' and its inclusion in a volume devoted to the limnology of saline lakes therefore seems appropriate.

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