New Zealand Journal of Marine and Freshwater Research abstracts

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Use of relative specific growth rates of periphytic diatoms to assess enrichment of a stream

BARRY J. F. BIGGS

Hydrology Centre, Division of Water Sciences Department of Scientific and Industrial Research P.O. Box 22-037, Christchurch, New Zealand

Abstract Relative specific growth rates of periphytic diatoms were investigated as a time-integrated measure of stream enrichment in the South Brook, Canterbury, New Zealand. The control site was expected to show phosphorus (P) limitation of growth rates with dissolved reactive P (DRP) of 6-10 (ig H; and the impact site, downstream of a discharge, was expected to show no growth limitation by P with DRP > 150 |j.g I"¹. Specific growth rates (p.) were generally high at the upstream site (jj. = 0.45-0.59 divd~') but the relative specific growth rates indicated that the cellular level kinetics were not limited by nutrient availability (i.e., \i: |i_niM_p > 0.8). Laboratory and field bioassays were carried out and all corroborated this interpretation, indicating that the discharge should have no effect on the growth rates of the downstream communities. As predicted, no significantdifferences occurred in growth between sites. It is concluded that relative specific growth rates could be useful to assist with impact monitoring of nutrient-enriched discharges.

Keywords growth rates; nutrients; phosphorus; assays; streams; biomass; stream ecology; periphyton; algae M89036 Received 11 July 1989; accepted 6 September 1989

New Zealand Journal of Marine and Freshwater Research, 1990, Vol. 24: 9-18 ; Crown copyright 1990
Received 11 July 1989; accepted 6 September 1989

PDF file of entire paper: medium quality (726K); (scanned from paper original: notes about this process)

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