New Zealand Journal of Marine and Freshwater Research abstracts
M99024Received 3 May 1999, accepted 11 September 2000
Effects of desiccation on stream epilithic algae
THORSTEN D. MOSISCH*
Centre for Catchment and In-Stream Research
Australian School of Environmental Studies
Griffith University
Nathan, Q 4111
Australia
*Present address: South East Queensland Water Corporation, P.
O. Box 236, Brisbane, Q 4002, Australia. email: tmosisch@seqwco.com.au
Abstract The effect of desiccation on epilithic algae was
studied in two subtropical rainforest streams in south-east Queensland,
Australia. Diatom-dominated algal assemblages on stream-collected cobbles were
subjected to desiccation periods of 15 and 30 days, followed by re-immersion in
the streams for 15 and 30 days. Algal assemblages in the two streams showed
different responses to the desiccation and re-immersion treatments, most likely
the result of differences in the physical and chemical characteristics of the
two stream ecosystems. Following the re-immersion treatments, chlorophyll
a was significantly reduced in one stream, with no significant changes
recorded in ash-free dry mass. In the second stream, epilithon ash-free dry
mass had increased significantly by the end of the re-immersion period, while
no significant effects of desiccation were measured. Results indicated that, at
least in one stream studied, diatom assemblages on the experimental cobbles
were not able to withstand short periods of desiccation (15 days) and did not
recover after 30 days of re-immersion in the streams. The results obtained here
showed that desiccation must be considered an important factor controlling
epilithon communities in streams.
Keywords ash-free dry mass; biomass; chlorophyll a;
desiccation; diatoms; disturbance; epilithon; streams
New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35: 173-180
0028-8330/01/3501-0173 $7.00 (c) The Royal Society of New Zealand 2001
PDF file of entire paper: medium quality (550K); (scanned from paper original: notes about this process)
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