In pollen preparations other microfossils
of various origin are also preserved. Among the 'extra' microfossils
in raised bog peat are spores of fungi, remains of algae and invertebrates.
In a series of papers the descriptions and illustrations of many
non-pollen palynomorphs (NPP, or 'Types') were published and their
indicator value was discussed (for references see van Geel, 2001).
Morphological descriptions were always combined with stratigraphic
information, often in the form of pollen and macrofossil diagrams.
Several hundred Types have now been distinguished, each one with
a Type-number. In most cases there was initially no, or hardly
any taxonomic/ecological knowledge about the distinguished Types.
The identification of the fossils was attempted with the aid of
literature and by consulting colleagues in invertebrate zoology,
phycology and mycology. Among the NPP there still are many taxa
which are not properly identified, but some of them nevertheless
can be used as palaeoenvironmental indicators. In such cases,
the ecological information was inferred from the co-occurrence
(curve matching) with identified taxa.
For Types in raised bog peat the publication by van Geel (1978) is relevant. For the ACCROTELM project only a selection of Types with a clear indicator value will be recorded (see below).
Many different fungal 'Types' occur in peat
deposits, especially in peat layers which were formed under relatively
dry conditions. In peat which was formed under very wet conditions
fungal remains occur rarely.
From the various studies of fossil fungal spores, it became clear that the recorded spores in most cases are of strictly local occurrence. They were fossilised at, or near the place where they had been produced, or the spores were deposited only a short distance from the place where sporulation took place. A relevant selection of raised bog fungi is given here. ACCROTELM partners responsible for pollen analysis will receive an illustration showing the following NPP:
spores (Types 1 and 2) indicate relatively dry conditions.
Spores are ellipsoidal, 22-30(-37) x 14-20(-24) µm. Spore surface almost black, evenly ornamented with ca 1 µm wide round, or ellipsoidal hyaline pits.
- Type 10 is an indicator
for relatively dry conditions. It occurs on the roots of Calluna
Spores transversely (1-)2-3(-6) septate, (10-)20-30(-50) µm long and (7-)9-10(-12) µm wide, formed at the ends of septate, pigmented, (1-)1.5(-2) µm wide hyphae; basal cells paler (thinner-walled) than the others; not constricted at the septa or hardly so. In each septum a ca 0.3 µm wide pore.
- Type 12 is also a dryness
indicator. It grows on a variety of bog plants.
Spores curved, (7-)10-13(-14) µm long, with two transverse septa, constricted at the septa. Apical cell (4-)6-7(-8) µm wide, thick-walled, dark brown, with a sub-apical germ pore about 0.7 µm wide. Central cell brown; basal cell hyaline and thin-walled.
- Spores of Meliola niessleana
(Type 14). The fungus is a parasite on Calluna vulgaris.
Spores 41-55 x 14-18 µm, three-septate, inequilateral (one side almost straight), slightly constricted at the septa. Septa thickened around the ca 1.5 µm wide pore.
- Spores of Neurospora
(Type 55C) indicate local bog fires.
Spores ellipsoidal, non-septate, brown, 22-28 x 15-18 µm, with two protruding apical pores, about 1 µm wide; with about 16 fine, longitudinal grooves.
Some algal spores:
- The hyaline spores of Mougeotia, Spirogyra and Zygnema-type are produced by filamentous green algae, inhabiting shallow, stagnant, oxygen-rich freshwater pools.
- Spores of Mougeotia are square, laterally straight to concave; retuse angles often with depressions. Surface smooth or with small pits.
- Spores of Spirogyra are ellipsoidal. Walls are smooth or reticulate; spores show a longitudinal furrow which often encircles almost the whole spore.
- Spores of Zygnema-type are spheroidal and flattened, with pits all over the surface.
Testate Amoebae in pollen slides:
- The thecae of Amphitrema flavum and Assulina indicate local relatively wet conditions. Many species of Testate Amoebae do not 'survive' the pollen preparation method. See Charman et al. (2000) for illustrations and ecological information and a complete analysis of Testates.
Counting of microfossils should be continued until at least 400 pollen grains of taxa included in the pollen-sum are recorded. Pollen-sum taxa are: trees, shrubs and upland herbs. Aquatic plants, local bog plants (like Cyperaceae and Ericales) and spores are excluded from the pollen-sum. However, their percentages will be expressed on the pollen-sum.
Some spores (like Types 10 and 12) can be so frequent that counting them until the pollen-sum is reached is too time-consuming. Therefore counting of these highly frequently occurring spores can be stopped when 50 pollen-sum taxa (or a certain number of the added Lycopodium spores) are recorded. Before entering the data in the TILIA program (for drawing diagrams) the number of spores should be 'extrapolated' first, so that (rough) percentages can be calculated.
Please note that Bas van Geel (IBED-FNWI, Kruislaan 318, 1098 SM Amsterdam, Netherlands; e-mail: email@example.com) is always willing to help in case of doubts about identification of non-pollen palynomorphs. If necessary samples can be photographed and sent as electronic attachments (.jpg files with compression so that the files are less than 1Mb).
Hendon, D. and Woodland, W.A. 2000. The identification
of testate amoebae (Protozoa) in peats. QRA Technical Guide
No. 9, Quaternary Research Association, London. 147 pp.
Transeau, E.N. 1951. The Zygnemataceae. Columbus Graduate School Monographs, Contributions in Botany, 1. Columbus, Ohio, 327 pp.
van Geel, B. 1978. A palaeoecological study of Holocene peat bog sections in Germany and the Netherlands. Rev. Palaeobot. Palynol. 25, 1-120.
van Geel, B. 1986. Application of fungal and algal remains and other microfossils in palynological analyses. In Berglund, B.E. (ed) Handbook of Holocene Palaeoecology and Palaeohydrology. Wiley, Chichester. p. 497-505.
van Geel, B., Pals J.P., van Reenen G.B.A. and van Huissteden J. 1995. The indicator value of fossil fungal remains, illustrated by a palaeoecological record of a Late Eemian/Early Weichselian deposit in the Netherlands. In Herngreen, G.F.W. & L. van der Valk (eds) Neogene and Quaternary geology of North-West Europe. Meded. Rijks Geol. Dienst 52: 297-315.
van Geel, B. and Grenfell H.R. 1996. Spores of Zygnemataceae. In Jansonius, J. & D.C. McGregor (eds) Palynology: principles and applications, Am. Ass. Strat. Palynol. Found., Vol. 1: 173- 179.
van Geel, B. 2001. Non-pollen palynomorphs. In: J.P. Smol, H.J.B. Birks and W.M. Last (eds.) Tracking environmental change using lake sediments.; Volume 3: Terrestrial, algal and silicaceous indicators. Kluwer, Dordrecht, p. 99-119.
For those who are interested to see more
NPP's from various sediment types:
Ask Bas van Geel for a copy of a xerox-copy book showing hundreds of NPP.