A technique for culturing enchytraeid worms on coniferous litter

Soil Biol. Biochem. Vol. 18. No. I, pp. 123-124, 1986 Printed in Great Britain

0038-0717/86 $3.00 + 0.00 Pergamon Press Ltd

S H O R T COMMUNICATION

A T E C H N I Q U E FOR C U L T U R I N G E N C H Y T R A E I D WORMS ON CONIFEROUS LITTER BRYAN S. GRIFFITHS a n d CLARE E. ALEXANDER Department of Microbiology, Macaulay Institute for Soil Research, Aberdeen AB9 2Q J, U.K.

(Accepted 16 July 1985)

A study of nutrient leaching of coniferous litter led to the observation that significant numbers of live enchytraeids were leached out of the litter over a period of several weeks. An experiment was then designed to test whether the system could be used as a simple method to culture and collect enchytraeids. The experimental design is shown in Fig. I. Open-ended glass leaching columns (dia 45 m m , length 390 mm) containing litter were held in a rack, beneath which were set collecting bottles. Both columns and bottles were covered with black vinyl to exclude light. A peristaltic p u m p (Newton Instrument Co. Ltd, Merseyside, England) automatically delivered 2 ml distilled water to each column every hour. To ensure an even distribution of water through the

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columns a disc of glass fibre paper ( W h a t m a n GF/A) was placed on top of the litter. Five columns were filled with 100 g of fresh litter collected from beneath a mixed plot of Sitka spruce [Picea sitchensis (Bong.) Carr.] and Scots pine (Pinus syh'estris L.) from Culloden forest, Inverness-shire, Scotland. The number of enchytraeids in the litter at the start of the experiment was determined by hand sorting three 10g sub-samples. The columns were held at 20'C for 13 weeks, then the final number of enchytraeids was determined in three 10 g subsamples from each column, using a wet funnel extraction method (O'Connor, 1962). During the incubation the enchytraeids collected in the leachate were counted twice weekly. Samples of enchytraeids were examined microscopically to determine whether there was any change in species composition. The number of enchytraeids in the litter was significantly greater (P < 0.001) at 13 weeks than at the start of the experiment (Table I). The numbers of enchytraeids in the leachate generally increased during the incubation with the total (number in litter + total number leached) being over 1000 per column by the end of incubation (Table 1). There was no apparent change in the type of enchytraeid present during the experiment, all specimens having simple sigoid setae in bundles of three. In a second experiment of similar design, litter was collected from beneath Sitka spruce at Fetteresso forest, Aberdeenshire, and from beneath Scots pine at Hazlehead, Aberdeenshire, Scotland. Thirty columns containing 25 g

Table i. Numbers of enchytraeids in, and leached from litter collected from beneath a mixed stand of Sitka spruce and Scots pine over a 13-week period at 20'C Sample Litter Leachate

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Fig. I. Leaching column used for culturing enchytraeid WOITflS. © The Macaulay Institute for Soil Research, 1986.

Litter + total leached 123

Week 0 13

Number column i _+SE 63 __.30 725 + 83

n 3 5 5

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7+2

2 3 4 5 6 7 8 9 10 II 12 13

5+2 30-+3 39 -+8 20 -+4 15+4 20+7 57 -+ 20 62-+21 75 +_ 18 102 -+ 18 121 -+ 23 106 -+ 23

13

1384 -+ 109

5

124

Short communications dry weight litter (approximately 100 g fresh wt) were incubated at 20 C. Ten replicate columns contained either spruce, pine or mixed (1:1 dry wt) litter. The number of enchytraeids present in the leachate was counted weekly. The results (Fig. 2) show that after an initial reduction, numbers leached increased to a m a x i m u m and then declined. More enchytraeids were leached from the mixed litter (up to 150 week ' ) than from spruce litter (up to 70 week L) (Fig. 2). N u m b e r s leached from pine litter were low throughout the incubation ( < 20 week t ). Tile total number of enchytraeids at the end of the incubation (number in litter + number leached) was > 1000 column ' in thc mixed litter, which was significantly (P < 0.05) greater than that in the spruce litter (approximately 500 column '), which in turn was significantly greater (P < 0.01) than that in pine litter ( < 6 0 column m). The results of these experinaent suggest that the choice of substrate is critical for the culture of enchytraeids, but with a suitable substrate this method allows the easy collection of large numbers of live enchytraeids for experimental purposes. In addition the method has potential as a means of studying enchytraeid biology under controlled conditions using natural substrates.

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Acknowledgement--This work was partly financed by the • ..~- . . . . . . . .

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Research and Development Programme of the European Economic Community.

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Fig. 2. N u m b e r of enchytraeids leached from Sitka spruce litter ( - - O - - L Scots pine litter (. • • - -) or a I:I mixture of these litters ( - - A - - ) over a 21-week period at 20 C + SE.

REFERENCE

O ' C o n n o r F. B. (1962) The extraction of Enchytraeidae from soil. In Progress in Soil Zoology (P. W. Murphy, Ed.), pp. 279-285. Butterworths, London.