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Updated 8/30/99

Microfossil Analysis


Overview

Paleoecological microfossils other than pollen which can be found in standard pollen preparations include: moss spores, fungi, algae, rhizopods, and other palynomorphs. Fungal spores are ubiquitous in standard pollen preparations and provide a remarkable range of ecological information. We have noted abrupt changes in frequency of fungal hyphae in microfossil preparations in Arctic peat sediments, which may be correlated with changes in carbon accumulation . If the variations in microfossils can be correlated with long term variations in peat vegetation and climate, we will have developed a powerful tool for studying the relationship between vegetation, carbon accumulation rates, and climate. Few studies currently exist in the Arctic which compare pollen changes with fungal abundance; but it has great potential and should be further investigated.

Charcoal, burned plant material, and specific fungal remains are all sources of information about past fire which can be derived from the paleoecological record. fungal ascospores are associated with the occurrence of local bog fires . Fungal spore frequencies may be a more reliable method of recognizing fire disturbance through time, than the current, rather unsatisfactory method of counting charcoal remains.

Danish investigators have shown how hyphae fragments may be used to determine stages of soil development and the relation of soil development to biological activity . Anderson found a characteristic difference between the length of hyphae fragments in brown earth soils as opposed to podzolic soils, and from this determined that former soil conditions could be traced by measuring these fungal fragments, a possibility that could be useful for future paleoecological soil analysis in the arctic.

Several fossilized blue-green algae, or cyanobacteria, which are a primary source of nitrogen fixation in the Arctic , and therefore of great interest regarding vegetation response to nutrient availability. Most cyanobacteria are infrequent in acidic soils, but those of the Anabaena genera, as well as some others, flourish in acid peats and are retrievable in the fossil record . Cyanobacteria, as well as green algae, which are often detectable in peats, are sensitive to changes in trophic conditions, such as eutrophism, and are useful as indicators of nutrient limiting systems.

Rhizopods (Testacea) are single-celled, molluscan amoebae widely used as an index of paleohydrological changes in peatlands and lakes (Heathwaite, 1990 #4554; Tolonen, 1986 #4553). They are well-preserved in ombrotrophic peats, resistant to humification and mineralization, relatively easy to identify to species, and highly sensitive to changes in moisture conditions. A number of rhizopods have already been identified from sites in Barrow, Meade River, and the White Hills sites, and have proven very useful in our interpretations . We anticipate that rhizopods will be highly diagnostic for our stratigraphic identification of thaw lake formation.

Microfossil Reference Collection:   A collection
of photographs of selected microfossils.

Microfossil Reading:  Suggested reading for those
wishing to know more about microfossil ananlysis.

Site prepared by Wendy Eisner
offering additonal information on microfossil research.